Stylus and sensor controller

ABSTRACT

A processor of a stylus according to the present disclosure detects a first signal supplied to a sensor electrode group in each frame. The processor determines whether the first signal represents a setting instruction of a local ID, and writes a value of the local ID specified by the setting instruction in a memory if the first signal is determined to represent the setting instruction. The processor repeatedly detects a second signal supplied to the sensor electrode group in each of one or more slots included in the frame. The processor compares values of a local ID included in the detected second signal and the local ID stored in the memory every time the processor detects the second signal, and transmits a first downlink signal to a sensor controller using an electrode if the values correspond with each other.

BACKGROUND Technical Field

The present disclosure relates to a stylus and a sensor controller andparticularly relates to a stylus and a sensor controller that arecompatible with simultaneous use of plural styluses (multi-stylus).

Background Art

An active capacitive system is known as one of a plurality of concretesystems of a position detecting system that enables handwriting input bya stylus on a touch surface provided on a surface of electronicequipment. Hereinafter, the stylus compatible with the active capacitivesystem will be referred to as the “active stylus.”

The active stylus is configured to be capable of transmitting a signal(downlink signal) to electronic equipment. The transmission of thedownlink signal is carried out by supplying a transmission signal to anelectrode provided at the tip of the active stylus and therebygenerating an electric field according to the signal in a space near theelectrode. The electronic equipment has a sensor board including anelectrode group in a matrix manner disposed on the lower side of a touchsurface and a sensor controller connected to this sensor board, and isconfigured to receive the downlink signal through detection, by thesensor controller, of change in the amount of charge generated in theelectrode group in the sensor board due to the above-describedalternating electric field. One example of the downlink signal isdisclosed in PCT Patent Publication No. WO 2015/111159. The downlinksignal according to this example is composed of an unmodulatedcontinuous signal for position detection (position signal) and a signalmodulated based on data such as writing pressure information and aunique identifier (ID) (data signal).

In the active capacitive system, the sensor controller in the electronicequipment is also configured to be capable of transmitting a signal(uplink signal) to the active stylus. The sensor controller transmitsthe uplink signal toward the stylus by supplying a transmission signalto the electrode group that forms the sensor board and therebygenerating an electric field on a panel. The active stylus is configuredto detect the uplink signal by detecting the amount of charge induced inthe above-described electrode by this electric field. In U.S. PatentApplication Publication No. 2013/0106797, an example of the activestylus that receives the uplink signal is described.

Incidentally, in recent years, the case in which the touch surfacedoubles as a liquid crystal display surface as in a so-called tabletcomputer has been increasing. In this case, the sensor board is disposedon or inside the liquid crystal panel. The position detecting system inwhich the sensor board is placed on the liquid crystal panel is calledthe “out-cell type.” In Japanese Patent Laid-Open No. 1993-6153 and PCTPatent Publication No. WO 2015/141349, an example of the positiondetecting system of the out-cell type is disclosed. Furthermore, amongthe position detecting systems in which the sensor board is placed inthe liquid crystal panel are the “on-cell type” in which the electrodegroup for the sensor board is disposed on a color filter glass orsubstrate glass inside the liquid crystal panel and the “in-cell type”in which common electrodes or pixel electrodes of the liquid crystalpanel double as part of the electrode group for the sensor board. In“JDI, LG, Sharp no Sumaho Muke In-cell/On-cell Senryaku wo Yomu” (inEnglish, “See the Strategy of In-cell/On-cell for Smartphones of JapanDisplay Inc., LG Electronics Incorporated, and Sharp Corporation”),[online], Nikkei Technology Online, [retrieved on Aug. 16, 2016],Internet<URL:http://techon.nikkeibp.co.jp/article/NEWS/20150121/400160/>,examples of the position detecting systems of the on-cell type and thein-cell type are disclosed.

In the position detecting system of the out-cell type or the on-celltype, it is known that a drive signal in the liquid crystal panel thatexists under the sensor board becomes noise and affects the operation ofthe sensor controller. A representative one of such noise is an ACcomponent of a voltage signal supplied to electrodes for driving thepixels of the liquid crystal panel. This voltage signal is a signal forcontrolling the orientation of the liquid crystal of the respectivepixels and enters the electrode group that forms the sensor board due toalternating current (AC) coupling to become noise. Furthermore, in theposition detecting system of the in-cell type, the electrode groupshared for both driving operation of the pixels and position detectionoperation can not be used for the position detection operation while thedriving operation of the pixels is being carried out.

In view of the above-described problems of the case in which the touchsurface doubles as the liquid crystal display surface, in recent years,studies have been made on a system in which communication between anactive stylus and a sensor controller is carried out by framecommunication in which the display operation period of a liquid crystalpanel is defined as one frame and each of plural blank periods (periodsin which the occurrence frequency of liquid crystal noise is relativelylow) that periodically appear in the one frame is defined as one slot.

Here, as one of specifications required for the position detectingsystem, there is a specification that plural styluses can besimultaneously used (multi-stylus). Therefore, studies are being made onmaking also the above-described frame communication compatible with themulti-stylus. According to the studies, a sensor controller broadcastsan uplink signal for ordering allocation of a slot to each stylus oneach frame basis. Then, each stylus transmits a downlink signal by usingthe allocated slot. This makes it possible to implement communicationbetween plural active styluses and the sensor controller in atime-sharing manner.

However, if the allocation of a slot is ordered to each stylus by theuplink signal of each frame fixed at not only the display operation rateor the like but any time cycle, the allocation of the slots to therespective styluses depends on the fixed frame rate. That is, in theabove-described system that is being studied, there is a problem thatthe allocation of the slots to the respective styluses can not beflexibly changed in a shorter time than the frame. Furthermore, there isa problem that the scan rate of each stylus is fixed to an integralmultiple of the frame rate.

Moreover, in the above-described system that is being studied, there isalso a problem that the size of the uplink signal that is transmitted inone frame and is for ordering allocation of plural slots inevitablybecomes large. If the size of the uplink signal is large, the occupancyratio of the uplink signal in one frame becomes high and thecommunication efficiency decreases. Furthermore, it takes a timeequivalent to several frames to perform processing of transmitting asignal with a large size to each of plural styluses and checking whetheror not setting has been reflected. Thus, the delay time until theallocation of the transmission time is actually reflected in allstyluses become long. In the case in which a user uses plural stylusesand a device such as an electronic ruler in such a manner as tofrequently make them to come close to and get remote from electronicequipment, this delay time possibly affects a feeling of use of theuser.

Furthermore, there is an electronic ruler made in imitation of a rulerof stationery as one kind of stylus. The movement velocity of a stylusof a general pen type while the stylus is being used is high. Incontrast, a drawing auxiliary device such as the electronic ruler is putat the same place for a while once being put on a panel surface and isused at lower movement velocity compared with the pen-type stylus inmany cases. Therefore, it is desirable that the scan rate can be changedaccording to the device type.

Moreover, differently from the pen-type stylus used while being heldwith a hand, the drawing auxiliary device such as the electronic ruleris used in such a manner as to remain placed on the panel surface evenwhile a user is not operating the drawing auxiliary device in somecases. Carrying out transmission and reception of signals between theauxiliary device and the sensor controller in such a case increases thepower consumption of the auxiliary device and consumes communicationresources between the sensor controller and the stylus (pen type orauxiliary device) even when the electronic ruler is not used.

BRIEF SUMMARY

Therefore, one of objects of the present disclosure is to provide astylus and a sensor controller with which allocation of the transmissiontime to each stylus can be flexibly changed with a shorter time than aframe and can be reflected in each stylus.

Furthermore, one of other objects of the present disclosure is toprovide a stylus and a sensor controller with which the size of anuplink signal for ordering allocation of the transmission time can bemade small.

Moreover, one of further other objects of the present disclosure is toallow the scan rate to be changed according to the type of device andcharacteristics of the use form.

In addition, one of further other objects of the present disclosure isto implement reduction in the power consumption of an auxiliary deviceand effective use of communication resources in the case in which theauxiliary device is left on a panel surface. A stylus according to thepresent disclosure is a stylus that operates in synchronization with asensor controller connected to a sensor electrode group, and is a stylusincluding an electrode, a memory, and a processor that, in operation:detects a first signal supplied to the sensor electrode group in eachframe of a plurality of frames; determines whether the first signalrepresents a setting instruction of a local ID, and writes a value ofthe local ID specified by the setting instruction to the memory if thefirst signal is determined to represent the setting instruction;repeatedly detects a second signal supplied to the sensor electrodegroup in each of one or more slots included in the frame; comparesvalues of a local ID included in the second signal detected and thelocal ID stored in the memory every time the processor detects thesecond signal; and transmits a first downlink signal to the sensorcontroller using the electrode if the values correspond with each other.

Furthermore, a sensor controller according to the present disclosure isa sensor controller that detects one or more styluses by using a sensorelectrode group. The sensor controller includes a processor; and amemory storing processor readable instructions that, when executed bythe processor, cause the sensor controller to: transmit a first signalthat represents a setting instruction that gives a local ID to a stylusthat has not been detected in each frame of a plurality of frames,transmit a second signal including the local ID regarding which aninstruction of setting has been made by the setting instruction to astylus that has been detected in each of a plurality of slots includedin the frame, and detect a first downlink signal transmitted from thestylus in response to the second signal.

A stylus according to an aspect of the present disclosure is a stylusthat bidirectionally transmits and receives a signal with a sensorcontroller connected to a sensor by using capacitive coupling and is astylus including a memory that temporarily stores a value of a local IDand a processor that determines whether or not an uplink signal that isdetected includes the value of the local ID stored in the memory everytime the uplink signal transmitted by the sensor controller is detected,and generates a downlink signal based on a handling state and transmitsthe downlink signal to the sensor controller if determining that theuplink signal that is detected includes the value of the local ID storedin the memory.

In the above-described stylus, the processor may generate the downlinksignal including the value of the local ID stored in the memory andtransmit the downlink signal to the sensor controller.

A sensor controller according to another aspect of the presentdisclosure is a sensor controller that has a function of detecting oneor more styluses and reports the positions of one or more styluses thathave been already detected to a host processor and is a sensorcontroller including a memory that stores values of one or more localIDs allocated to a respective one of the one or more styluses that havebeen already detected and a processor that decides a scan rate abouteach of the one or more styluses that have been already detected, andselects any one of the values of the one or more local IDs stored in thememory based on the scan rate that is decided, and transmits an uplinksignal including the selected value of the local ID, and derives theposition of a stylus corresponding to the selected value of the local IDbased on a downlink signal returned in response to the uplink signal.

In the above-described sensor controller, the processor may decide thescan rate about each of the one or more styluses that have been alreadydetected based on a device type of each of the one or more styluses thathave been already detected.

An auxiliary device according to the present disclosure may include aruler part, a plurality of electrodes provided at the ruler part, areceiving electrode for receiving an uplink signal transmitted from asensor controller, and a processor that transmits a signal to the sensorcontroller while sequentially switching the plurality of electrodes inresponse to reception of the uplink signal.

Furthermore, an auxiliary device according to the present disclosure mayinclude a ruler part, two or more electrodes provided at the ruler part,a first switch that is provided on a top surface of the ruler part andis for switching whether the electronic ruler is in a working state orin a stop state by operation by a user, and a processor that transmits adownlink signal to the sensor controller by using the two or moreelectrodes if the first switch is in the working state, and stopstransmission processing of the downlink signal if the first switch is inthe stop state.

According to the present disclosure, the sensor controller transmits theuplink signal (second signal) including the value of a local ID at everytransmission clock time and thereby the stylus that should transmit thedownlink signal (first downlink signal) in the slot can be specified.Therefore, it becomes possible to flexibly change allocation of thetransmission time to each stylus with a shorter time than the framewithout depending on the frame. Furthermore, the state about theschedules is not stored on the stylus side and therefore the time forchanging them is unnecessary. This can improve the response speed as thewhole system regarding change in the scan rate and so forth necessary inthe case in which a new stylus is detected, or the like. Moreover, byonly making one value of a local ID be included in the uplink signal, itbecomes possible to order allocation of the transmission time from thesensor controller to each stylus. Thus, it becomes possible to decreasethe size of the uplink signal for ordering allocation of pluraltransmission times in the frame.

Furthermore, according to the present disclosure, the stylus generatesthe downlink signal including the value of the local ID temporarilystored in the memory and transmits the downlink signal to the sensorcontroller. Therefore, even when the downlink signals are detected atplural places on the panel surface, the sensor controller candiscriminate them on each stylus basis. In addition, the number of bitsof the local ID can be made smaller compared with the global ID to bedescribed later. This makes it possible to lower the downlink occupancyratio necessary for transmitting the local ID.

Moreover, according to the present disclosure, the sensor controllerdecides the scan rate about each of one or more styluses that have beenalready detected based on the device type of each of the one or morestyluses that have been already detected. Thus, it becomes possible tochange the scan rate according to the type of the device andcharacteristics of the use form.

Furthermore, according to the present disclosure, the auxiliary deviceis provided with the first switch for switching whether the first switchis in the working state or in the stop state by operation by a user.Therefore, reduction in the power consumption of the auxiliary deviceand effective use of communication resources in the case in which theauxiliary device is left on the panel surface are implemented.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram depicting a position detecting system according toan embodiment of the present disclosure;

FIG. 2 is a diagram depicting a detailed configuration of a firstexample of styluses depicted in FIG. 1;

FIG. 3 is a diagram depicting a detailed configuration of a secondexample of the styluses depicted in FIG. 1;

FIG. 4 is an explanatory diagram of a six-axis inertial measurement unit(IMU) depicted in FIG. 3;

FIG. 5 is a diagram depicting a detailed configuration of a stylus(ruler-type device) depicted in FIG. 1;

FIG. 6 is a top view of a stylus (ruler-type device) depicted in FIG. 1;

FIG. 7 is a diagram depicting the detailed configuration of electronicequipment depicted in FIG. 1;

FIG. 8 is a diagram depicting an ID management table depicted in FIG. 7;

FIG. 9 is a flowchart depicting a processing flow of a sensor controllerdepicted in FIG. 1;

FIG. 10 is a flowchart depicting a detailed flow of setting instructiontransmission processing depicted in FIG. 9;

FIG. 11 is a flowchart depicting a detailed flow of command signaltransmission processing depicted in FIG. 9;

FIG. 12 is a flowchart depicting the detailed flow of the command signaltransmission processing depicted in FIG. 9;

FIG. 13 is a flowchart depicting the detailed flow of the command signaltransmission processing depicted in FIG. 9;

FIG. 14 is a flowchart depicting the detailed flow of the command signaltransmission processing depicted in FIG. 9;

FIG. 15 is a flowchart depicting the detailed flow of the command signaltransmission processing depicted in FIG. 9;

FIG. 16 is a flowchart depicting a processing flow of the stylusesdepicted in FIG. 1;

FIG. 17 is a flowchart depicting a detailed flow of command signalreception processing depicted in FIG. 16;

FIG. 18 is a flowchart depicting the detailed flow of the command signalreception processing depicted in FIG. 16;

FIG. 19 is a flowchart depicting the detailed flow of the command signalreception processing depicted in FIG. 16;

FIG. 20 is a flowchart depicting the detailed flow of the command signalreception processing depicted in FIG. 16;

FIG. 21 is a timing chart depicting signals transmitted and receivedbetween the stylus and the sensor controller depicted in FIG. 1 (scenein which the sensor controller newly registers the stylus);

FIG. 22 is a timing chart depicting signals transmitted and receivedbetween the styluses and the sensor controller depicted in FIG. 1 (scenein which the sensor controller further registers the other stylus afterregistering the stylus);

FIG. 23 is a timing chart depicting signals transmitted and receivedbetween the styluses and the sensor controller depicted in FIG. 1 (scenein which the sensor controller readjusts the transmission schedule basedon the device type of each of the styluses);

FIG. 24 is a timing chart depicting signals transmitted and receivedbetween the styluses and the sensor controller depicted in FIG. 1 (scenein which normal writing by the styluses is being carried out after thesensor controller has readjusted the transmission schedule based on thedevice type of each of the styluses);

FIG. 25 is an explanatory diagram of cancellation of registration of alocal ID by the sensor controller 31 and the stylus 2 a depicted in FIG.1;

FIG. 26 is a timing chart depicting signals transmitted and receivedbetween the styluses 2 a and 2 b and the sensor controller 31 depictedin FIG. 1 (scene in which the styluses 2 a and 2 b simultaneouslyrespond to one setting instruction);

FIG. 27 is a timing chart depicting signals transmitted and receivedbetween the styluses 2 a and 2 b and the sensor controller 31 depictedin FIG. 1 (scene in which the styluses 2 a and 2 b having the same localID simultaneously respond to one data transmission instruction) and thestate of the styluses 2 a and 2 b;

FIG. 28 is a timing chart depicting signals transmitted and receivedbetween the styluses 2 a and 2 b and the sensor controller 31 accordingto a first modification example of the embodiment of the presentdisclosure (scene in which the sensor controller 31 newly registers thestylus 2 b);

FIG. 29 is a timing chart depicting signals transmitted and receivedbetween the styluses 2 a and 2 c and the sensor controller 31 accordingto the first modification example of the embodiment of the presentdisclosure (scene in which normal writing by the styluses 2 a and 2 c isbeing carried out);

FIG. 30 is a timing chart depicting another example of signalstransmitted and received between the stylus 2 a, 2 b, or 2 c and thesensor controller 31 according to the first modification example of theembodiment of the present disclosure;

FIG. 31 is a timing chart depicting signals transmitted and receivedbetween the stylus 2 a, 2 b, or 2 c and the sensor controller 31according to a second modification example of the embodiment of thepresent disclosure; and

FIG. 32 is a flowchart depicting a processing flow of the stylus 2 a, 2b, or 2 c according to a third modification example of the embodiment ofthe present disclosure.

DETAILED DESCRIPTION

A preferred embodiment of the present disclosure will be described indetail below with reference to the accompanying drawings.

FIG. 1 is a diagram depicting the whole of a position detecting system 1according to the present embodiment. As depicted in this diagram, theposition detecting system 1 is configured to include two pen-typestyluses 2 a and 2 b, one ruler-type stylus 2 c, and electronicequipment 3. The styluses 2 a, 2 b, and 2 c are collectively referred toherein as stylus 2. The electronic equipment 3 is configured to includea sensor electrode 30, a sensor controller 31, a panel 32, an electronicequipment controller 33 (host processor), and a liquid crystal displaydevice 34.

In the position detecting system 1, the sensor controller 31 is a masterand the one or more styluses 2 are slaves. The position detecting system1 is so configured that, when a polling request (command signal to bedescribed later) including a local ID is issued from the sensorcontroller 31, only the stylus 2 having the local ID included in it ispermitted to make a reply (transmission of a downlink signal DS to bedescribed later) in the period of response to the polling. Every timethe stylus 2 detects the polling request, the stylus 2 determineswhether or not the detected polling request includes the value of thelocal ID stored by its own self. If determining that the polling requestincludes the value of the local ID, the stylus 2 transmits the downlinksignal DS. The local ID is given to each stylus 2 by the sensorcontroller 31 and is stored by the stylus 2.

The styluses 2 a to 2 c are all the above-described active stylus andare used simultaneously or separately by one or more users. Hereinafter,in some cases, the styluses 2 a to 2 c will be represented as the stylus2 when there is no need to particularly discriminate the styluses 2 a to2 c.

For example when using the stylus 2 a, a user gradually brings thestylus 2 a close to the panel surface of the panel 32 (pen-down. In FIG.1, represented as “DOWN”) and finally brings the pen tip of the stylus 2a into contact with the panel surface (pen touch). Then, when the usermoves the pen tip on the panel surface while keeping this contact state(pen move), a locus st1 of the movement is rendered on the panel surfaceby processing of the electronic equipment 3 as depicted in the diagram.This rendering is continued until the user separates the pen tip of thestylus 2 a from the panel surface (pen-up. In FIG. 1, represented as“UP”). Thereafter, when the user carries out pen-down, pen touch, penmove, and pen-up again, a locus st2 of the movement is similarlyrendered on the panel surface by processing of the electronic equipment3. In FIG. 1, a locus st3 generated by pen-down, pen touch, pen move,and pen-up of the stylus 2 b is also diagrammatically represented.

The stylus 2 c, details of which will be described later, is a specialdevice (auxiliary device) having plural electrodes disposed to be linedin a straight line manner. Although being a device for digitalstationery referred to as the “electronic ruler” typically, this devicewill be referred to as the stylus 2 c for simplification of explanationof operation in the present specification. The electronic equipment 3 isconfigured to be capable of accepting input of a straight line by thestylus 2 c. Specifically, the electronic equipment 3 is configured torender a virtual line X parallel to the straight-line-shaped pen tip ofthe stylus 2 c on the panel surface when a user brings the pen tip intocontact with the panel surface (pen touch).

The styluses 2 a to 2 c are each configured to detect an uplink signalUS supplied by the sensor controller 31 of the electronic equipment 3through the sensor electrode 30 and transmit the downlink signal DS as aresponse to the predetermined uplink signal US. The downlink signal DSis received by the sensor electrode 30 and is supplied from the sensorelectrode 30 to the sensor controller 31.

As the uplink signal US, two kinds of signals, a stylus search signaland a command signal, exist. The stylus search signal is a signal fornewly detecting the undetected stylus 2 and is composed of a knowndetection pattern c1 and a delimiter pattern STP added to the tail end.The detailed contents of the detection pattern c1 and the delimiterpattern STP will be described later. The stylus 2 is configured tointermittently carry out detection operation of the detection patternc1, and detects the existence of the sensor controller 31 when detectingthe detection pattern c1. Furthermore, the stylus 2 that has detectedthe detection pattern c1 continues the detection operation withoutchange and synchronizes with the sensor controller 31 based on thetiming when the delimiter pattern STP is detected.

Meanwhile, the command signal is a signal for conveying an instruction(command) to the stylus 2 and is configured to include information(local ID) to identify one stylus 2 among one or more styluses 2 thatare presently on the panel surface and an instruction (command) to theidentified stylus 2. The stylus 2 acquires a command included in acommand signal and performs processing according to the contents thereofif the command signal including the local ID of this stylus 2 isreceived. In this processing, transmission processing of the downlinksignal DS is included. The local ID is information with which it isenough that the sensor controller 31 can identify one stylus 2 among oneor more styluses 2 that are presently on the panel surface. Thus, itsuffices for the local ID to be information with a smaller number ofbits compared with a global ID to be described later. Preferably, thelocal ID is information that takes a value of at most 4 bits, with which16 styluses 2 can be identified. 0000b, 1111b, or the like among 4-bitlocal IDs may be used as a special local ID to identify all orundetected styluses 2 like a so-called broadcast address. Furthermore,in the respective diagrams to be described later, the local ID will berepresented as “LID” (abbreviation for local identifier) and the globalID will be represented as “GID” (abbreviation for global identifier).

The downlink signal DS is configured to include a burst signal formed ofan unmodulated carrier signal and a data signal formed of a carriersignal modulated based on data (including the local ID allocated to thestylus 2 that has transmitted the downlink signal DS) according to acommand. The stylus 2 is configured to transmit the burst signal atfirst and subsequently transmit the data signal when transmitting thedownlink signal DS. The sensor controller 31 of the electronic equipment3 is configured to detect the existence of the stylus 2 and the positionthereof by receiving the burst signal by using the sensor electrode 30.Indicated positions P1 and P2 depicted in FIG. 1 represent examples ofthe position detected in this manner. The above-described loci st1 tost3 are the loci of movement of these indicated positions P1 and P2.

In order for the sensor controller 31 to detect the stylus 2, the stylus2 needs to come close to the touch surface of the electronic equipment 3to such an extent that the sensor controller 31 can receive the downlinksignal DS. A sensing range SR depicted by a dashed line in FIG. 1 iswhat schematically represents the range in which the sensor controller31 can receive the downlink signal DS. When the stylus 2 enters thissensing range SR, the sensor controller 31 receives the downlink signalDS through the sensor electrode 30 and thereby becomes capable ofdetecting the stylus 2. The above-described “pen-down” means such motionof the stylus 2 as to move into the sensing range SR from the outside.Normally the pen-down is carried out by operation of bringing the stylus2 close to the panel surface of the electronic equipment 3 by a user.The state in which the stylus 2 has entered the sensing range SR by thepen-down but has not yet gotten contact with the panel surface isreferred to as the “hover state.”

On the other hand, in some cases, the stylus 2 can receive the uplinksignal US transmitted by the sensor controller 31 even when outside ofthe sensing range SR. This is because the uplink signal US can betransmitted by using all of the electrodes in a matrix manner disposedin parallel to the panel surface and can be transmitted with higherintensity compared with the downlink signal DS transmitted from anelectrode 21 (described later) near the tip of the stylus 2. An uplinkdetection height AH depicted in the diagram represents the limit of theheight (distance from the panel surface) at which the stylus 2 canreceive the uplink signal US. The uplink detection height AH is at ahigher position (position farther from the panel surface) than the upperlimit of the sensing range SR.

FIG. 2 is a diagram depicting the detailed configuration of a firstexample of the styluses 2 a and 2 b depicted in FIG. 1. The styluses 2 aand 2 b depicted in this diagram are configured to have a core body 20a, the electrode 21, a switch 22, a writing pressure detecting sensor 23(writing pressure detecting circuit), and a signal processing circuit24.

The core body 20 a is an electrically-conductive member that forms thepen tip of the stylus 2 and doubles as the electrode 21. The electrode21 plays a role as an antenna for transmitting the downlink signal DSand also plays a role as an antenna for receiving the uplink signal UStransmitted from the sensor controller 31 through the sensor electrode30. The core body 20 a and the electrode 21 may be formed as differentmembers as in FIG. 3 to be described later. Furthermore, an electrode totransmit the downlink signal DS and an electrode to receive the uplinksignal US may be separately provided.

The switch 22 is a switch that takes either the on-state or theoff-state by operation by a user, such as a side switch provided on theside surface of the stylus 2 or a tail switch provided at the rear endpart. The writing pressure detecting sensor 23 is a pressure sensor fordetecting the pressure (writing pressure) applied to the tip of the corebody 20 a. Specifically, the writing pressure detecting sensor 23 can beformed by using a publicly-known technique such as avariable-capacitance capacitor whose capacitance changes according tothe pressure or a pressure sensor whose resistance value changesaccording to the pressure for example.

The signal processing circuit 24 has functions of receiving the uplinksignal US from the sensor controller 31 through the electrode 21 toperform processing according to the contents thereof and generating thedownlink signal DS to be transmitted to the sensor controller 31 totransmit the downlink signal DS toward the sensor controller 31 throughthe electrode 21. Specifically, the signal processing circuit 24 isconfigured to include a switch 40, a receiver 41, a controller 44, and atransmitter 46 functionally. Each of them will be described below inturn.

The switch 40 is a one-circuit-two-contact switch element configured insuch a manner that a common terminal is connected to either one of aT-terminal and an R-terminal. The common terminal of the switch 40 isconnected to the electrode 21. The T-terminal is connected to the outputterminal of the transmitter 46 and the R-terminal is connected to theinput terminal of the receiver 41. The state of the switch 40 iscontrolled by a control signal SWC from the controller 44. In the caseof receiving the uplink signal US from the sensor controller 31, thecontroller 44 controls the switch 40 by the control signal SWC so thatthe R-terminal may be connected to the common terminal. Furthermore, inthe case of transmitting the downlink signal DS to the sensor controller31, the controller 44 controls the switch 40 by the control signal SWCso that the T-terminal may be connected to the common terminal. In theinitial state, i.e. in the period until the stylus 2 detects thedetection pattern c1 to be described later, the controller 44 oftenbecomes a sleep state in which the on-state and the sleep-state arerepeated to carry out reception operation only intermittently in orderto reduce the power consumption of the stylus 2, after fixing the switch40 to the state in which the R-terminal is connected to the commonterminal.

The circuit receiver 41 is a circuit that carries out reception of asignal supplied from the circuit switch 40 (signal that has arrived atthe electrode 21) and decoding of a chip sequence included in thereceived signal. In this example, the circuit receiver 41 is configuredto include a waveform regenerating circuit 42 and a correlationarithmetic circuit 43. The receiver 41 is configured to be capable ofeach detecting the above-described detection pattern c1, the delimiterpattern STP, the local ID, and the command by this decoding. Thereceiver 41 carries out the reception operation only intermittentlyuntil the detection pattern c1 is detected in order to reduce the powerconsumption of the stylus 2 as described above.

The waveform regenerating circuit 42 binarizes the level of the charge(voltage) induced in the electrode 21 with a clock of several times (forexample four times) the chip rate of a spreading code PN (describedlater) used when the sensor controller 31 carries out spreading of theuplink signal US to shape the level into a binary sequence (chipsequence) of positive and negative polarity values and output the binarysequence. The correlation arithmetic circuit 43 decodes the chipsequence included in the received signal by storing the chip sequenceoutput by the waveform regenerating circuit 42 in a register andperforming correlation operation with the spreading code PN (or codeobtained by carrying out at least either one of inversion and cyclicshift for this spreading code PN) while sequentially shifting the chipsequence with the above-described clock.

The receiver 41 sequentially carries out determination of whether or notthe values of symbols obtained by the decoding of the correlationarithmetic circuit 43 represent the detection pattern c1. When detectingthe detection pattern c1 as the result, the receiver 41 detects theexistence of the sensor controller 31 and issues, to the controller 44,an activation signal EN for enabling execution of processing or the likeaccording to a command represented by a command signal.

Furthermore, if the detection pattern c1 is detected, the receiver 41switches the reception operation from intermittent operation tocontinuous operation based on an instruction from the controller 44activated by the above-described activation signal EN and sequentiallycarries out determination of whether or not the values of symbolsobtained by decoding represent the above-described delimiter patternSTP. When detecting the delimiter pattern STP as the result, thereceiver 41 outputs a detection clock time t2 thereof to the controller44.

The receiver 41 after detecting the delimiter pattern STP carries outreception operation of the command signal transmitted by the sensorcontroller 31 in accordance with control by the controller 44.Specifically, the receiver 41 acquires a set of a local ID and controlinformation c2 (information including an instruction by the sensorcontroller 31) from the values of a series of symbols obtained by thecorrelation arithmetic circuit 43 while the reception operation is beingcarried out, and outputs the set to the controller 44.

The controller 44 is formed of a microprocessor (MCU) and is triggeredto be activated by supply of the activation signal EN from the receiver41. The controller 44 includes a processor and a memory storingprocessor readable instructions that, when executed by the processor,cause the sensor controller to perform processing described herein. Inthe processing performed by the activated controller 44, besides theabove-described switching from intermittent reception operation tocontinuous reception operation, processing of causing the receiver 41 toreceive a command signal, processing of deciding its own local ID andtemporarily storing the local ID in a memory 45, and processing ofcausing the transmitter 46 to transmit the downlink signal DS areincluded. In the processing of causing the receiver 41 to receive acommand signal, processing of supplying the control signal SWC forconnecting the R-terminal to the common terminal to the switch 40 isincluded. Similarly, in the processing of causing the transmitter 46 totransmit the downlink signal DS, processing of supplying the controlsignal SWC for connecting the T-terminal to the common terminal to theswitch 40 is included.

When being supplied with the detection clock time t2 from the receiver41, first the controller 44 performs the processing of causing thereceiver 41 to receive a command signal. As described in detail later,the sensor controller 31 is configured to transmit a command signal thatrepresents a setting instruction of the local ID (uplink signal fordetecting a new stylus that is not included in one or more styluses thathave been already detected) immediately after transmitting the stylussearch signal composed of repetition of the detection pattern c1 and thedelimiter pattern STP. When receiving the command that represents thissetting instruction from the receiver 41, the controller 44 decides thelocal ID represented by the command as its own local ID and stores thelocal ID in its own memory 45 in the initial state in which a local IDhas not yet been stored in the memory 45. From then on, every time a setof a local ID and a command is supplied from the receiver 41 to thecontroller 44, the controller 44 determines whether or not the local IDtherein corresponds with the local ID stored in the memory 45 andperforms processing according to the command included in the set(including the processing of causing the transmitter 46 to transmit thedownlink signal DS) only if the local IDs correspond with each other.Furthermore, the controller 44 performs processing of deleting the localID stored in the memory 45 if a predetermined time has elapsed from thelast reception of supply of the set of a local ID and a command. Thememory 45 holds the value of the local ID given by the sensor controller31 only temporarily and therefore may be a volatile memory differentlyfrom a global ID storage device 51 to be described later.

In the downlink signal DS, which the transmitter 46 is caused totransmit by the controller 44, a burst signal and a data signal areincluded as described above. When causing the burst signal to betransmitted, the controller 44 causes the transmitter 46 to transmit anunmodulated carrier signal. On the other hand, when transmitting thedata signal, the controller 44 acquires data instructed to betransmitted by a command supplied from the receiver 41 and supplies thedata to the transmitter 46 together with the local ID stored in thememory 45. Due to this, the downlink signal DS to be transmitted fromthe transmitter 46 becomes a signal including the data instructed to betransmitted by the command and the local ID. In the data instructed tobe transmitted by the command, data based on the handling state of thestylus 2 at the timing when the command is received, such as data thatrepresents the on-/off-state of the switch 22 and data that represents awriting pressure detected by the writing pressure detecting sensor 23,is included.

The transmitter 46 is a circuit that generates the downlink signal DSaccording to control by the controller 44 and supplies the downlinksignal DS to the electrode 21, and is composed of a modulating circuit47 and a booster circuit 48.

The modulating circuit 47 is a circuit that generates a carrier signal(for example square wave signal) with a predetermined frequency or afrequency in accordance with control from the controller 44 and outputsthe carrier signal as it is or after modulating it based on control bythe controller 44. The modulating circuit 47 at the time of transmissionof the burst signal outputs the carrier signal as it is withoutmodulation in accordance with an instruction of the controller 44. Asignal obtained by modulation with a pattern of known values may be usedas the burst signal, and the modulating circuit 47 in this case outputsthe carrier signal after modulating it with the above-described patternof known values. On the other hand, the modulating circuit 47 at thetime of transmission of the data signal modulates (on-off-keying (OOK),phase-shift keying (PSK), or the like) the carrier signal based on datasupplied from the controller 44 and outputs a modulated signal obtainedas the result.

The booster circuit 48 is a circuit that generates the downlink signalDS by boosting the output signal of the modulating circuit 47 to certainamplitude. The downlink signal DS generated by the booster circuit 48 issent out from the electrode 21 to a space through the switch 40.

FIG. 3 is a diagram depicting the detailed configuration of a secondexample of the styluses 2 a and 2 b depicted in FIG. 1. The styluses 2 aand 2 b depicted in this diagram are different from the styluses 2 a and2 b depicted in FIG. 2 in that the core body 20 a and the electrode 21are formed of different members and a six-axis inertial measurement unit(IMU) 50 and the global ID storage device 51 are included in the signalprocessing circuit 24. In the following, description will be made withfocus on the differences from the styluses 2 a and 2 b depicted in FIG.2.

The core body 20 a according to the present example is formed of aninsulating member that forms the pen tip of the stylus 2. The electrode21 is an electrically-conductive member provided near the tip of thecore body 20 a. The role of the electrode 21 is the same as theelectrode 21 depicted in FIG. 2.

The six-axis IMU 50 is an inertial measurement unit including athree-axis acceleration sensor and a three-axis gyro sensor and isconfigured to output a value that represents a measurement result to thecontroller 44.

FIG. 4 is an explanatory diagram of the six-axis IMU 50. FIG. 4A depictsa diagram obtained when the stylus 2 a or 2 b is viewed from a lateralside and FIG. 4B depicts a section of the stylus 2 a or 2 bcorresponding to line A-A depicted in FIG. 4A.

As depicted in FIG. 4A, the six-axis IMU 50 uses the longitudinaldirection of the stylus 2 a or 2 b as the Z-axis. Furthermore, asdepicted in FIG. 4B, the six-axis IMU 50 uses the direction from thecenter of the section of the stylus 2 a or 2 b toward the switch 22 asthe Y-axis and uses the direction perpendicular to both the Z-axis andthe Y-axis as the X-axis. The six-axis IMU 50 acquires the accelerationand angular velocity of the stylus 2 a or 2 b regarding the direction ofeach of these axes including X-axis to Z-axis and outputs theacceleration and the angular velocity to the controller 44.

Referring back to FIG. 3, the global ID storage device 51 stores aglobal ID that is information different for each stylus 2. The global IDis e.g. 64-bit information that represents an identifier of the vendorof the stylus 2, an identification number of the stylus 2 in the vendor,the device type of the stylus 2 (pen type, ruler type, or the like), andso forth. The global ID is written to the global ID storage device 51 atthe timing of manufacturing of the stylus 2. As the global ID storagedevice 51, a non-volatile memory is used differently from the volatilememory 45. The global ID and the local ID are different from each otherin that the global ID is an identifier that includes the identifier ofthe vendor and so forth and is globally unique whereas the local ID isan identifier for the sensor controller 31 to locally identify one ofplural styluses 2 that exist in the detection range of the sensorcontroller 31.

If the styluses 2 a and 2 b have the configuration depicted in FIG. 3,in the data instructed to be transmitted by the sensor controller 31with a command signal, the measurement result of the six-axis IMU 50 andthe global ID are included in addition to the above-described data basedon the handling state of the stylus 2. The controller 44 in the case inwhich the controller 44 is instructed to transmit the measurement resultof the six-axis IMU 50 acquires data that represents the measurementresult from the six-axis IMU 50 and supplies the data to the transmitter46 as data of the transmission target. Similarly, the controller 44 inthe case in which the controller 44 is instructed to transmit the globalID reads out the global ID from the global ID storage device 51 andsupplies the global ID to the transmitter 46 as data of the transmissiontarget.

FIG. 5 is a diagram depicting the detailed configuration of the stylus 2c (ruler-type device) depicted in FIG. 1. Furthermore, FIG. 6 is a topview of the stylus 2 c. As depicted in these diagrams, the stylus 2 c isdifferent from the styluses 2 a and 2 b depicted in FIG. 3 in that thestylus 2 c has a ruler 20 b (ruler part) instead of the core body 20 a,in that the stylus 2 c has n electrodes 21_1 to 21_n, in that the stylus2 c has a switch 27, in that the stylus 2 c has two switches 25 and 26instead of the switch 22 and the writing pressure detecting sensor 23,and in that the stylus 2 c does not have the six-axis IMU 50. In thefollowing, description will be made with focus on the differences fromthe styluses 2 a and 2 b depicted in FIG. 3.

The ruler 20 b is an insulating member having a thin plate shape and ismade in imitation of a ruler of stationery. The electrodes 21_1 to 21_nare each an electrically-conductive member having a thin plate shape andare disposed at at least two places at one end and the other end of theruler 20 b in the longitudinal direction. In the example of FIG. 5,three or more electrodes 21 are disposed to be lined at equal intervalsinside the ruler 20 b from one end to the other end of the ruler 20 b inthe longitudinal direction along the longitudinal direction of the ruler20 b. Furthermore, in the example of FIG. 6, two electrodes 21 aredisposed at one end and the other end, respectively, of the ruler 20 bin the longitudinal direction. The electrodes 21_1 to 21_n each play arole as an antenna for transmitting the downlink signal DS and also playa role as an antenna for receiving the uplink signal US transmitted fromthe sensor controller 31 through the sensor electrode 30 similarly tothe electrode 21 depicted in FIG. 2 and FIG. 3. The electrode 21 may beused exclusively for transmission and a receiving electrode may beseparately provided. In this case, the receiving electrode may receivethe uplink signal US by another proximity wireless communication measuresuch as Bluetooth (registered trademark) for example.

The switch 27 is a one-circuit-n-contact switch element configured insuch a manner that a common terminal is connected to any one of nelectrode-side terminals. The common terminal of the switch 27 isconnected to the common terminal of the switch 40 and the nelectrode-side terminals of the switch 27 are connected to theelectrodes 21_1 to 21_n in a one-to-one manner.

The switch 25 (first switch) is a switch for switching whether thestylus 2 c is in the working state or in the stop state. Furthermore,the switch 26 (second switch) is a switch for causing the electronicequipment 3 included in the sensor controller 31 to activatepredetermined processing such as settlement of a virtual line to bedescribed later. These switches 25 and 26 are provided on the topsurface of the ruler 20 b, preferably near the center in thelongitudinal direction, as exemplified in FIG. 6.

The controller 44 is configured to cause the transmitter 46 to transmitthe downlink signal DS every time a command corresponding to the localID allocated to its own self is supplied from the receiver 41 in theperiod from pushing of the switch 25 by a user until pressing-down ofthe switch 26 by the user. At this time, the switch 27 carries outoperation of switching the electrode-side terminal as the connectiontarget of the common terminal every time the downlink signal DS istransmitted. Due to this, the downlink signal DS is transmitted fromeach of the electrodes 21_1 to 21_n in turn.

The sensor controller 31 recognizes the stylus 2 c to be a ruler-typedevice by ordering transmission of the global ID by a command signal andchecking the global ID transmitted by the stylus 2 c in responsethereto. The sensor controller 31 is configured to store pluralpositions identified based on the downlink signal DS that issequentially received and display the virtual line X (see FIG. 1) thatlinks them regarding the stylus 2 c recognized to be a ruler-typedevice.

Furthermore, the controller 44 is so configured that, when the userpresses down the switch 26 (second switch), data indicating thispressing-down is made to be included in the downlink signal DS and thetransmitter 46 is caused to transmit the downlink signal DS. Byreceiving this data, the sensor controller 31 notifies the electronicequipment controller 33 of data for settling the position of the virtualline X.

The movement velocity of the pen-type stylus 2 like the styluses 2 a and2 b while the stylus 2 is being used is high. In contrast, theruler-type stylus 2 like the stylus 2 c is put at the same place for awhile once being put on a panel surface and is used at lower movementvelocity compared with the pen-type stylus 2 in many cases. Therefore, ahigh scan rate does not need to be allocated to the ruler-type stylus 2in many cases. Thus, the sensor controller 31 according to the presentembodiment sets the scan rate low regarding the stylus 2 recognized tobe a ruler type through a check of the global ID. Details thereof willbe described later.

Moreover, differently from the pen-type stylus 2 used while being heldwith a hand, the ruler-type stylus 2 is used in such a manner as toremain placed on the panel surface even while a user is not operatingthe ruler-type stylus 2 in some cases. Carrying out transmission andreception of signals between the ruler-type stylus 2 and the sensorcontroller 31 in such a case increases the power consumption of theruler-type stylus 2 and consumes communication resources between thesensor controller 31 and the respective styluses 2 even when theruler-type stylus 2 is not used. Therefore, the stylus 2 c according tothe present embodiment is configured to allow the user to specify thetransmission period of the downlink signal DS by operation of theswitches 25 and 26. Due to this, reduction in the power consumption ofthe stylus 2 c and effective use of communication resources in the casein which the stylus 2 c is left on the panel surface are implemented.

Next, FIG. 7 is a diagram depicting the detailed configuration of theelectronic equipment 3 depicted in FIG. 1. The configuration andoperation of the electronic equipment 3 will be described in detailbelow with reference to this FIG. 7.

The sensor electrode 30 is composed of plural linear electrodes 30X thateach extend in the X-direction and plural linear electrodes 30Y thateach extend in the Y-direction. The sensor electrode 30 is configured tobe capacitively coupled to the stylus 2 by these linear electrodes 30Xand 30Y. The above-described uplink signal US and downlink signal DS aretransmitted and received through this capacitive coupling.

As depicted in FIG. 7, the sensor controller 31 is configured to have anMCU 60, a logic circuit 61, a transmitter 62, a receiver 63, and aselection circuit 64.

The MCU 60 and the logic circuit 61 are controllers that controltransmission-reception operation of the sensor controller 31 bycontrolling the transmitter 62, the receiver 63, and the selectioncircuit 64. Specifically, the MCU 60 is a microprocessor that internallyhas a read only memory (ROM) and a random access memory (RAM) andoperates based on a predetermined program. Meanwhile, the logic circuit61 is configured to output control signals ctrl_t1 to ctrl_t4 and ctrl_rbased on control by the MCU 60.

As depicted in FIG. 7, the MCU 60 internally has a memory that stores anID management table 70. Furthermore, the MCU 60 is configured to have anID managing circuit 71, a position deriving circuit 72, and a statedetecting circuit 73 functionally.

FIG. 8 is a diagram depicting the ID management table 70. As depicted inthis diagram, the ID management table 70 is a table that stores,regarding each local ID, the global ID, the velocity, the present state,the operation state, reset command non-issuance flag 1, reset commandnon-issuance flag 2, a deletion counter, and a downlink signaltransmission schedule.

The ID managing circuit 71 has a function of carrying out registrationand deletion of local IDs stored in the ID management table 70.Specifically, the ID managing circuit 71 supplies the controlinformation c2 including a setting instruction of a local ID that hasnot yet been registered in the ID management table 70 to the transmitter62 and controls the transmitter 62 to transmit a command signal thatrepresents this control information c2. Then, when the stylus 2 that hasreceived this command signal transmits the downlink signal DS includingthe ordered local ID, the ID managing circuit 71 receives this downlinksignal DS through the receiver 63 and determines whether or not thelocal ID instructed to be set is included in it. If the result of thisdetermination is the positive result, the ID managing circuit 71performs processing of registering the value of the local ID in the IDmanagement table 70. As for deletion of a local ID, detailed descriptionwill be made later with reference to a flowchart of FIG. 12.

Furthermore, the ID managing circuit 71 also has a function ofsupplying, to the transmitter 62, the control information c2 including atransmission instruction of various kinds of data other than the localID (data that represents the on-/off-state of the switch 22 depicted inFIG. 2, data that represents the writing pressure detected by thewriting pressure detecting sensor 23 depicted in FIG. 2, data thatrepresents the measurement result of the six-axis IMU 50 depicted inFIG. 3, the global ID stored in the global ID storage device 51 depictedin FIG. 3, and so forth) and controlling the transmitter 62 to transmita command signal that represents this control information c2. At thistime, in the control information c2 supplied to the transmitter 62, thelocal ID of the stylus 2 as the destination of the transmissioninstruction is included. As described above, the stylus 2 is soconfigured that, only when the local ID included in the received commandsignal corresponds with the local ID allocated to its own self, thestylus 2 transmits the downlink signal DS including the local ID anddata instructed to be transmitted by a command. When receiving thedownlink signal transmitted in this manner through the receiver 63, theID managing circuit 71 performs processing of detecting the local ID andthe data included in it. Then, the ID managing circuit 71 reports, tothe electronic equipment controller 33 (see FIG. 1), the detected localID and data (in FIG. 7, represented as Res (that means response data))together with coordinates x and y derived by the position derivingcircuit 72 to be described later. Furthermore, if a global ID isincluded in the detected data, the ID managing circuit 71 also performsprocessing of writing the global ID to the ID management table 70.

Moreover, the ID managing circuit 71 also has a function of deciding thetransmission schedule of the downlink signal DS and writing thetransmission schedule to the ID management table 70 regarding each ofone or more local IDs stored in the ID management table 70. Thistransmission schedule is composed of two kinds of parameters, thetransmission frequency (scan rate) of the downlink signal DS and thetransmission continuation time of the downlink signal DS. By default,the ID managing circuit 71 sets each of items including the scan rateand the transmission continuation time of the downlink signal DS to anequal value regarding all local IDs registered in the ID managementtable 70.

Here, it is thought to suffice that the scan rate given to theruler-type stylus 2 is a smaller value compared with the pen-type stylus2. This is because, in the ruler-type stylus 2, movement on a panelsurface is thought to be less compared with the pen-type stylus 2. For asimilar reason, also regarding the stylus 2 depicted to be not in activemotion actually based on the movement velocity (what is calculated bythe state detecting circuit 73) to be described later, a lower scan rateis thought to be enough compared with the stylus 2 depicted to be inactive motion. Furthermore, the transmission continuation times of thedownlink signal DS according to the respective styluses 2 differdepending on the specifications of the respective styluses 2. Forexample, the stylus 2 of a certain vendor is configured to continuetransmission of the downlink signal DS for a double time compared withthe stylus 2 of another vendor.

Therefore, if the ID managing circuit 71 can acquire the global ID(device type) or the movement velocity of the stylus 2, the ID managingcircuit 71 decides the optimum scan rate and transmission continuationtime of the downlink signal DS for each stylus 2 based on them andcarries out readjustment of the transmission schedule of the downlinksignal DS based on the result thereof. To cite a concrete example, theID managing circuit 71 decides the scan rate about each of one or morelocal IDs stored in the ID management table 70 in such a manner that thescan rate becomes higher when the movement velocity is higher, andwrites the scan rate to the ID management table 70. Furthermore, inanother example, the ID managing circuit 71 decides the transmissioncontinuation time of the downlink signal DS of each stylus 2 based onthe device type of each stylus 2 and writes the transmissioncontinuation time to the ID management table 70. This readjustment willbe described in more detail later with reference to FIG. 23 and FIG. 24.

The transmission schedule of the downlink signal DS written to the IDmanagement table 70 is implemented through control, by the ID managingcircuit 71, of the transmission frequency of the command signaladdressed to each local ID and the transmission interval of the commandsignal. Specifically, the ID managing circuit 71 implements the scanrate set in the ID management table 70 by controlling the transmissionfrequency of the command signal addressed to each local ID. For example,if two local IDs #1 and #2 are set in the ID management table 70 and therespective scan rates are both 1/2, the ID managing circuit 71alternately transmits command signals addressed to a respective one oflocal IDs #1 and #2. Furthermore, if two local IDs #1 and #2 are set inthe ID management table 70 and the scan rate of local ID #1 is 1/4 andthe scan rate of local ID #2 is 3/4, the ID managing circuit 71transmits the command signal at such a frequency that the ID managingcircuit 71 transmits a command signal addressed to local ID #1 one timeand then transmits a command signal addressed to local ID #2 threetimes. Moreover, the ID managing circuit 71 implements the transmissioncontinuation time of the downlink signal DS set in the ID managementtable 70 by controlling the transmission interval of the command signal.Specifically, because the sensor controller 31 receives the downlinksignal DS during the transmission interval of the command signal, thetime of continuation of detection operation of the downlink signal DSbecomes longer when the transmission interval of the command signal isset longer for example. Therefore, a long transmission continuation timeof the downlink signal DS can be ensured. The sensor controller 31decides the polling schedule of issuance of the uplink signals US thatare transmission request commands including the respective IDs in such amanner that the downlink signal DS is transmitted from each stylus 2 ina form that matches such a transmission schedule of the downlink signalDS. In accordance with this polling schedule, the uplink signals USincluding the respective local IDs are transmitted.

The position deriving circuit 72 acquires the reception intensity of thedownlink signal DS at each of the respective plural linear electrodes30X and 30Y based on a digital signal supplied from the receiver 63, andperforms processing of deriving coordinates x and y that represent theposition of the stylus 2 based on the result.

The state detecting circuit 73 performs processing of calculating themovement velocity of each stylus 2 from change in the position derivedby the position deriving circuit 72 regarding each local ID and writingthe movement velocity to the ID management table 70. Furthermore, thestate detecting circuit 73 performs processing of, regarding each localID, determining whether or not the downlink signal DS as a response tothe uplink signal US has been received, and if the downlink signal DShas been received, determining whether the value of the writing pressureincluded in it is 0 or is larger than 0, and writing the result to theID management table 70 as the present state of the stylus 2.Specifically, as depicted in FIG. 8, a value that represents “reply touplink signal is absent” is written about the local ID regarding whichthe downlink signal DS as a response to the uplink signal US has notbeen received. A value that represents “pen-down state” is written aboutthe local ID regarding which the downlink signal DS as a response to theuplink signal US has been received. A value that represents “writingpressure=0” is further written about the local ID regarding which thevalue of the writing pressure is 0. A value that represents “writingpressure>0” is further written about the local ID regarding which thevalue of the writing pressure is larger than 0.

Furthermore, the state detecting circuit 73 performs processing of,regarding each local ID, acquiring the operation state, reset commandnon-issuance flag 1, reset command non-issuance flag 2, and the deletioncounter and writing them to the ID management table 70. Details of themwill be described more specifically later with reference to processingflowcharts of the sensor controller 31.

The transmitter 62 is a circuit that generates the uplink signal US inaccordance with control by the MCU 60 and the logic circuit 61. Asdepicted in FIG. 7, the transmitter 62 is configured to include apattern supply circuit 80, a switch 81, a code sequence holding circuit82, a spreading processing circuit 83, and a transmission guard circuit84. Particularly regarding the pattern supply circuit 80 among them,description will be made based on the assumption that it is included inthe transmitter 62 in the present embodiment. However, the patternsupply circuit 80 may be included in the MCU 60.

In the uplink signal US, two kinds of signals, the stylus search signaland the command signal, are included as described above. Furthermore,the stylus search signal of them is composed of repetition of thepredetermined detection pattern c1 and the predetermined delimiterpattern STP disposed at the tail end.

The detection pattern c1 is a pattern of the values of symbols used fordetection of the existence of the sensor controller 31 by the stylus 2and is made known to the stylus 2 in advance (before the stylus 2detects the sensor controller 31). The symbol is the unit of informationused for modulation in transmission processing (unit of informationexpressed by a transmission signal) and is the unit of informationobtained by demodulating one symbol that is a received signal inreception processing. The value of the system can include a valueconverted to a bit sequence (hereinafter, referred to as “bit sequencecorresponding value”) and a value that is not converted to a bitsequence by the stylus 2 that has received the symbol (hereinafter,referred to as “bit sequence non-corresponding value”). In a concreteexample, the detection pattern c1 is formed of a pattern “PM” arisingfrom coupling of two kinds of bit sequence non-corresponding values “P”and “M.”

The delimiter pattern STP is a pattern of the values of the symbols fornotifying the stylus 2 of the end of the repetition period of thedetection pattern c1 and is formed of a pattern that does not appear inthe repetition of the detection pattern c1. The delimiter pattern STP isalso made known to the stylus 2 in advance (before the stylus 2 detectsthe sensor controller 31). To cite one example, in the case of formingthe detection pattern c1 by “PM,” a coupling of two bit sequencenon-corresponding values “P” and “M,” as described above, the delimiterpattern STP can be formed of a pattern “PP” obtained by continuing thebit sequence non-corresponding value “P” twice. By interchanging theconfigurations of the delimiter pattern STP and the detection patternc1, the delimiter pattern may be formed by “PM” and the detectionpattern c1 may be formed by “PP.”

The pattern supply circuit 80 holds the detection pattern c1 and thedelimiter pattern STP and is configured to output them in predeterminedorder in accordance with an instruction of the control signal ctrl_t1supplied from the logic circuit 61. Specifically, the pattern supplycircuit 80 is configured to repeatedly output the detection pattern c1continuously during a predetermined continuous transmission period andoutput the delimiter pattern STP immediately after the end of thecontinuous transmission period. Due to this, transmission of the stylussearch signal is implemented.

The switch 81 has a function of selecting either one of the patternsupply circuit 80 and the MCU 60 based on the control signal ctrl_t2supplied from the logic circuit 61 and supplying the selected one outputto the spreading processing circuit 83. If the switch 81 selects thepattern supply circuit 80, the detection pattern c1 or the delimiterpattern STP is supplied from the pattern supply circuit 80 to thespreading processing circuit 83. On the other hand, if the switch 81selects the MCU 60, the control information c2 is supplied from the MCU60 to the spreading processing circuit 83.

The control information c2 is information including a settinginstruction of a local ID or a transmission instruction of various kindsof data other than the local ID as described above. The controlinformation c2 is different from the detection pattern c1 and thedelimiter pattern STP in that the value thereof is not shared with thestylus 2 in advance. The control information c2 is transmitted in such amanner as to be associated with the values (for example 0 to 15) ofsymbols associated with a bit sequence for example.

The code sequence holding circuit 82 has a function of generating andholding a spreading code PN with a predetermined chip length havingautocorrelation characteristics based on the control signal ctrl_t3supplied from the logic circuit 61. The spreading code PN held by thecode sequence holding circuit 82 is supplied to the spreading processingcircuit 83.

The spreading processing circuit 83 has a function of obtaining atransmission chip sequence with a predetermined chip length bymodulating the spreading code PN held by the code sequence holdingcircuit 82 based on the values of the symbols supplied through theswitch 81 (detection pattern c1, delimiter pattern STP, or controlinformation c2). The spreading processing circuit 83 is configured tosupply the acquired transmission chip sequence to the transmission guardcircuit 84.

The transmission guard circuit 84 has a function of inserting a guardperiod necessary for switching between transmission operation andreception operation (period during which neither transmission norreception is carried out) between the transmission period of the uplinksignal US and the reception period of the downlink signal DS based onthe control signal ctrl_t4 supplied from the logic circuit 61.

The receiver 63 is a circuit for receiving the downlink signal DStransmitted by the stylus 2 based on the control signal ctrl_r of thelogic circuit 61. Specifically, the receiver 63 is configured to includean amplification circuit 85, a detection circuit 86, and ananalog-digital (AD) converter 87.

The amplification circuit 85 amplifies and outputs the downlink signalDS supplied from the selection circuit 64. The detection circuit 86 is acircuit that generates a voltage corresponding to the level of theoutput signal of the amplification circuit 85. The AD converter 87 is acircuit that generates a digital signal by sampling the voltage outputfrom the detection circuit 86 at predetermined time intervals. Thedigital signal output by the AD converter 87 is supplied to the MCU 60.The MCU 60 acquires data (local ID, global ID, writing pressure, and soforth) transmitted by the stylus 2 based on the digital signal suppliedin this manner.

The selection circuit 64 is configured to include switches 88 x and 88 yand conductor selecting circuits 89 x and 89 y.

The switches 88 x and 88 y are each a one-circuit-two-contact switchelement configured in such a manner that a common terminal is connectedto either one of a T-terminal and an R-terminal. The common terminal ofthe switch 88 x is connected to the conductor selecting circuit 89 x andthe T-terminal is connected to the output terminal of the transmitter 62and the R-terminal is connected to the input terminal of the receiver63. Furthermore, the common terminal of the switch 88 y is connected tothe conductor selecting circuit 89 y and the T-terminal is connected tothe output terminal of the transmitter 62 and the R-terminal isconnected to the input terminal of the receiver 63.

The conductor selecting circuit 89 x is a switch element for selectivelyconnecting the plural linear electrodes 30X to the common terminal ofthe switch 88 x. The conductor selecting circuit 89 x is configured tobe also capable of simultaneously connecting part or all of the plurallinear electrodes 30X to the common terminal of the switch 88 x.

The conductor selecting circuit 89 y is a switch element for selectivelyconnecting the plural linear electrodes 30Y to the common terminal ofthe switch 88 y. The conductor selecting circuit 89 y is also configuredto be also capable of simultaneously connecting part or all of theplural linear electrodes 30Y to the common terminal of the switch 88 y.

To the selection circuit 64, four control signals sTRx, sTRy, selX, andselY are supplied from the logic circuit 61. Specifically, the controlsignals sTRx, sTRy, selX, and selY are supplied to the switch 88 x, theswitch 88 y, the conductor selecting circuit 89 x, and the conductorselecting circuit 89 y, respectively. The logic circuit 61 implementstransmission of the uplink signal US including the stylus search signaland the command signal and reception of the downlink signal DS includingthe burst signal and the data signal by controlling the selectioncircuit 64 by using these control signals sTRx, sTRy, selX, and selY.

More specifically, in the case of transmitting the stylus search signal,the logic circuit 61 controls the selection circuit 64 in such a mannerthat all of the plural linear electrodes 30Y (or all of the plurallinear electrodes 30X) are connected to the output terminal of thetransmitter 62. Furthermore, in the case of transmitting the commandsignal, the logic circuit 61 controls the selection circuit 64 in such amanner that a predetermined number of electrodes that exist near aposition derived at the last minute regarding the stylus 2 of thetransmission target among the respective plural linear electrodes 30Xand 30Y are connected to the output terminal of the transmitter 62.

The logic circuit 61 in the case of receiving the burst signal controlsthe selection circuit 64 in such a manner that all of the respectiveplural linear electrodes 30X and 30Y are sequentially connected to theinput terminal of the receiver 63 while the transmission of the burstsignal is continuing. This allows the MCU 60 to acquire the receptionintensity of the burst signal at each of the respective plural linearelectrodes 30X and 30Y and thus it becomes possible to derive theposition of the stylus 2 as described above. On the other hand, thelogic circuit 61 in the case of receiving the data signal controls theselection circuit 64 in such a manner that only one electrode closest toa position derived by the immediately-previous burst signal regardingthe stylus 2 that transmits the data signal among the respective plurallinear electrodes 30X and 30Y is connected to the input terminal of thereceiver 63. This makes it possible to fully utilize the transmissiontime of the data signal for sending data from the stylus 2 to the sensorcontroller 31.

The configurations and operation of the stylus 2 and the electronicequipment 3 that form the position detecting system 1 are described indetail above. Next, operation of the stylus 2 and the sensor controller31 relating to the present disclosure will be described in more detailwith reference to flowcharts of processing performed by the stylus 2 andthe sensor controller 31.

FIG. 9 to FIG. 15 are flowcharts depicting processing flows of thesensor controller 31. Furthermore, FIG. 16 to FIG. 20 are flowchartsdepicting processing flows of the stylus 2. Moreover, FIG. 21 to FIG. 24and FIG. 26 to FIG. 29 are time charts depicting signals transmitted andreceived between one or two of the styluses 2 a to 2 c and the sensorcontroller 31. Furthermore, FIG. 25 is an explanatory diagram ofcancellation of registration of a local ID by the sensor controller 31and the stylus 2 a. In the following, description will be made withreference to these diagrams.

First, as depicted in FIG. 9, the sensor controller 31 determineswhether the elapsed time from the previous transmission of the stylussearch signal is equal to or longer than a predetermined time or isshorter than the predetermined time (S1). The sensor controller 31 needsto transmit the stylus search signal every predetermined time fordetecting the stylus 2 that has not been detected, and determineswhether or not the transmission timing of this stylus search signal hascome at S1.

If determining at S1 that the elapsed time is equal to or longer thanthe predetermined time, the sensor controller 31 transmits the stylussearch signal (S2). In FIG. 21, the stylus search signal transmittedfrom the sensor controller 31 every predetermined time in this manner isdiagrammatically represented. After transmitting the stylus searchsignal, the sensor controller 31 returns the processing to S1.

If determining at S1 that the elapsed time is shorter than thepredetermined time, the sensor controller 31 determines whether or notthe present timing is immediately after transmission of the stylussearch signal (S3). As a result, the sensor controller 31 performssetting instruction transmission processing if determining that thepresent timing is immediately after transmission (S4), and performscommand signal transmission processing if determining that the presenttiming is not immediately after transmission (S5). If information of thecommand of the setting instruction can be made to be included in thestylus search signal, S4 and S5 may be deemed as one processing.

In FIG. 10, details of the setting instruction transmission processingare depicted. As depicted in this diagram, at first, the sensorcontroller 31 that has started the setting instruction transmissionprocessing decides a local ID #n of the setting target based on theregistration status of the local ID (S10). The check of the registrationstatus of the local ID is carried out by referring to the ID managementtable 70 depicted in FIG. 8. Subsequently, the sensor controller 31transmits a command signal that represents a setting instruction of thedecided local ID #n (S11). As depicted in FIG. 21, this command signalis continuously carried out from the transmission of the stylus searchsignal.

Next, the sensor controller 31 carries out reception operation of thedownlink signal DS (S12) and determines whether or not the downlinksignal DS including the local ID #n has been received (S13). In thiscase, the sensor controller 31 decodes a data signal in the downlinksignal DS to check whether or not the downlink signal DS includes thelocal ID #n. This point is the same also in reception determination inanother act to be described later.

If determining at S13 that the downlink signal DS including the local ID#n has not been received, the sensor controller 31 ends the settinginstruction transmission processing without executing further particularprocessing and returns to S1 in FIG. 9.

On the other hand, if determining at S13 that the downlink signal DSincluding the local ID #n has been received only at one place in thepanel surface, the sensor controller 31 registers the local ID #n in theID management table 70 (S14).

In FIG. 21, a scene in which the sensor controller 31 newly registersthe stylus 2 a is depicted. The initial state of this diagram is thestate in which no local ID is registered in the ID management table 70.The stylus 2 a that has received the stylus search signal due topen-down receives a command signal that represents a setting instructionof a local ID #1 subsequently. Then, the stylus 2 a transmits thedownlink signal DS including the local ID #1 in response to this commandsignal. In response to receiving this downlink signal DS, the sensorcontroller 31 registers the local ID #1 in the ID management table 70.

In FIG. 22, a scene in which the sensor controller 31 registers thestylus 2 a and thereafter further registers the stylus 2 b is depicted.The initial state of this diagram is the state in which the stylus 2 ahas been registered in FIG. 21 (state in which the local ID #1 has beenallocated to the stylus 2 a). Because the local ID #1 has been alreadyregistered in the ID management table 70, the command signal transmittedby the sensor controller 31 subsequently to the stylus search signal isa command signal that represents a setting instruction of a local ID #2.The stylus 2 b that has received the stylus search signal due topen-down receives the command signal that represents the settinginstruction of the local ID #2 subsequently. Then, the stylus 2 atransmits the downlink signal DS including the local ID #2 in responseto this command signal. In response to receiving this downlink signalDS, the sensor controller 31 registers the local ID #2 in the IDmanagement table 70.

Referring back to FIG. 10, the sensor controller 31 that has registeredthe local ID #n in the ID management table 70 at S14 derives theposition of the stylus 2 based on a burst signal in the receiveddownlink signal DS (S15). Furthermore, if a data signal in the downlinksignal DS includes data other than the local ID #n, the sensorcontroller 31 extracts the data (S16).

Moreover, in order to give opportunities for transmission of thedownlink signal DS to the stylus 2 corresponding to the newly-registeredlocal ID #n, the sensor controller 31 readjusts the transmissionschedule of the downlink signal DS and updates the ID management table70 based on the result thereof (S17).

Referring to FIG. 21 and FIG. 22 again, in the state of FIG. 21 in whichonly the local ID #1 is registered, all command signals excluding thecommand signal immediately after the stylus search signal are signalsaddressed to the local ID #1 (stylus 2 a). That is, the scan rate of thestylus 2 a is set to 1.

When the local ID #2 is newly registered as depicted in FIG. 22, thesensor controller 31 needs to give opportunities for transmission of thedownlink signal DS also to the local ID #2 (stylus 2 b). Therefore, inthe example of FIG. 22, the local ID #1 and the local ID #2 are giventhe scan rate of the same value(=1/2) to allow the styluses 2 a and 2 bto alternately transmit the downlink signal DS. As above, by default(state before the scan rates are decided based on the global ID or themovement velocity of the stylus 2), the sensor controller 31 decides thescan rate about each of one or more styluses that have been alreadydetected in such a manner that the scan rates about the respective oneof the one or more styluses that have been already detected are equal toeach other.

The readjustment of the transmission schedule at S17 in FIG. 10 iscarried out in order to give opportunities for transmission of thedownlink signal DS to the newly-registered stylus 2 as in this exampledepicted in FIG. 22. After the end of S17, the sensor controller 31 endsthe setting instruction transmission processing and returns to S1 inFIG. 9.

If determining at S13 that the downlink signal DS including the local ID#n has been received at plural places in the panel surface, the sensorcontroller 31 sets the value of the operation state of the local ID #nto “first reset mode” in the ID management table 70 (S18) and sets“TRUE” in reset command non-issuance flag 1 of the local ID #n (S19).The first reset mode is an operation mode for temporarily cancellingallocation of the local ID #n immediately after transmission of acommand signal that represents a setting instruction of the local ID #nas exemplified in FIG. 26. Reset command non-issuance flag 1 is binaryflag information that becomes “TRUE” when the reset order that should betransmitted in the first reset mode has not yet been transmitted andbecomes “FALSE” in the other case. Detailed contents of reset processingin which they are used will be described later with reference to FIG. 13and FIG. 14. After the end of S19, the sensor controller 31 ends thesetting instruction transmission processing and returns to S1 in FIG. 9.

Next, in FIG. 11, details of the command signal transmission processingare depicted. As depicted in this diagram, first the sensor controller31 that has started the command signal transmission processing decides(selects) a local ID #k as the transmission target of a command signalbased on the transmission schedule of each local ID registered in the IDmanagement table 70 (S20). Specifically, the sensor controller 31decides (selects) the local ID #k as the transmission target of acommand signal based on the scan rate that has been already decidedregarding each local ID. Then, by referring to the value of theoperation state in the ID management table 70 again, the sensorcontroller 31 determines which of “normal mode,” “first reset mode,” and“second reset mode” the value of the operation state of the local ID #kis (S21).

In FIG. 12, processing in the case in which the sensor controller 31 hasdetermined at S21 that the operation state of the local ID #k is the“normal mode” is depicted. As depicted in this diagram, first the sensorcontroller 31 in this case transmits a command signal that represents adata transmission instruction to the stylus 2 identified based on thelocal ID #k (S30). The data instructed to be transmitted here is forexample data that represents the handling state at the timing when thecommand signal that represents the data transmission instruction isreceived, such as data that represents the on-/off-state of the switch22 depicted in FIG. 2, data that represents the writing pressuredetected by the writing pressure detecting sensor 23 depicted in FIG. 2,and data that represents the measurement result of the six-axis IMU 50depicted in FIG. 3, and a global ID stored in the global ID storagedevice 51 depicted in FIG. 3, and so forth.

The sensor controller 31 that has transmitted the command signal at S30subsequently carries out reception operation of the downlink signal DS(S31) and determines whether or not the downlink signal DS including thelocal ID #k has been received (S32).

If determining at S32 that the downlink signal DS including the local ID#k has been received only at one place in the panel surface, first thesensor controller 31 sets 0 in the deletion counter of the local ID #kin the ID management table 70 (S33). The deletion counter is a counterthat represents the number of times of failure in reception of thedownlink signal DS in spite of trial of the reception and is providedfor each local ID. The deletion counter is reset to 0 if the downlinksignal DS including the corresponding local ID #k is received. If thedeletion counter of the local ID #k is 0, cancellation of registrationof the local ID #k is not carried out.

Next, the sensor controller 31 derives the position of the stylus 2based on a burst signal in the received downlink signal DS (S34) andextracts data included in a data signal in the downlink signal DS (S35).Moreover, the sensor controller 31 readjusts the transmission schedule(S36).

In FIG. 23, one example of the readjustment of the transmission schedulecarried out at S36 is depicted. In this example, the styluses 2 a and 2b simultaneously exist on the panel surface and the local IDs #1 and #2are given to the styluses 2 a and 2 b, respectively. Furthermore, thetransmission continuation time of the downlink signal DS by the stylus 2b (local ID #2) is set to two times the default value. The sensorcontroller 31 receives a global ID from the stylus 2 b and determinesthe device type of the stylus 2 b based on the received global ID. Then,from the determination result, the sensor controller 31 understands thefact that the transmission continuation time of the downlink signal DSby the stylus 2 b is two times the default value. Based on the factunderstood in this manner, the sensor controller 31 decides thetransmission schedule of the downlink signal DS of each local ID in sucha manner that the transmission continuation time of the downlink signalDS by the stylus 2 b becomes two times the default value, and sets thetransmission schedule in the ID management table 70. Then, from then on,the sensor controller 31 controls the transmission interval of thecommand signal in such a manner that the continuation period ofreception operation in the case of receiving the downlink signal DS fromthe stylus 2 b becomes two times the default value.

Here, in FIG. 23, the reception operation continuation time of thesensor controller 31 when the global ID is received is longer thanusual. This is because the global ID is data with as large a size as 64bits as described above. In order to receive the global ID, which islarge data as above, the sensor controller 31 extends the continuationperiod of reception operation carried out after transmission of acommand signal that represents a transmission instruction of the globalID according to the size of the global ID. The adjustment of thisreception operation continuation period is operation carried outseparately from the readjustment of the transmission schedule.

In FIG. 24, another example of the readjustment of the transmissionschedule carried out at S36 is depicted. In this example, the styluses 2a and 2 b simultaneously exist on the panel surface and the local IDs #1and #2 are given to the styluses 2 a and 2 c, respectively. The sensorcontroller 31 receives a global ID from each of the styluses 2 a and 2 c(not depicted) and thereby understands the fact that the stylus 2 a is apen-type device and the stylus 2 c is a ruler-type device. Based on thefact understood in this manner, the sensor controller 31 decides thetransmission schedule of the downlink signal DS of each local ID in sucha manner that the scan rate of the stylus 2 a becomes three times thescan rate of the stylus 2 c, and sets the transmission schedule in theID management table 70. Then, from then on, the sensor controller 31controls the transmission frequency of the command signal addressed toeach local ID in such a manner that the scan rate of the stylus 2 abecomes three times the scan rate of the stylus 2 c.

Referring back to FIG. 12, the sensor controller 31 that has readjustedthe transmission schedule at S36 ends the command signal transmissionprocessing and returns to S1 in FIG. 9.

On the other hand, if determining at S32 in FIG. 12 that the downlinksignal DS including the local ID #k has been received at plural placesin the panel surface, the sensor controller 31 sets 0 in the deletioncounter of the local ID #k in the ID management table 70 (S37).Furthermore, in the ID management table 70 likewise, the sensorcontroller 31 sets the value of the operation state of the local ID #kto “second reset mode” (S38) and sets “TRUE” in reset commandnon-issuance flag 2 of the local ID #k (S39). The second reset mode isthe same as the first reset mode set at S18 depicted in FIG. 10 in thatthe second reset mode is an operation mode for cancelling allocation ofthe local ID #k. However, the second reset mode is different from thefirst reset mode in that the second reset mode is an operation mode forcancelling allocation of the local ID #n with priority setting ifoverlapping is detected when command signals that represent (not asetting instruction but) a data transmission instruction are beingtransmitted to the local ID #n as exemplified in FIG. 27. Reset commandnon-issuance flag 2 is binary flag information that becomes “TRUE” whenthe reset order that should be transmitted in the second reset mode hasnot yet been transmitted and becomes “FALSE” in the other case. Detailedcontents of reset processing in which they are used will be describedlater with reference to FIG. 15. After the end of S39, the sensorcontroller 31 ends the command signal transmission processing andreturns to S1 in FIG. 9.

The sensor controller 31 in the case of determining at S32 in FIG. 12that the downlink signal DS including the local ID #k has not beenreceived determines whether or not the deletion counter of the local ID#k stored in the ID management table 70 is larger than a predeterminedthreshold D (S40). If determining that the deletion counter is notlarger, the sensor controller 31 increments the deletion counter of thelocal ID #k by 1 (S43). On the other hand, if determining that thedeletion counter is larger, the sensor controller 31 cancels theregistration of the local ID #k by deleting the row of the local ID #kfrom the ID management table 70 (S41). Then, in order to allocateopportunities for transmission of the downlink signal DS given to thestylus 2 corresponding to the local ID #k thus far to other styluses 2,the sensor controller 31 readjusts the transmission schedule of thedownlink signal DS and updates the ID management table 70 based on theresult thereof (S42).

The determination at S40 is, in short, processing of determining whetheror not the state in which a response to the command signal from thestylus 2 corresponding to the local ID #k is absent has continued alarger number of times than D times. If the state in which the responseis absent continues, the possibility that the stylus 2 has gotten out ofthe sensing range SR depicted in FIG. 1 is thought to be high.Therefore, the sensor controller 31 cancels the registration of thelocal ID #k in such a case. The sensor controller 31 that has ended theprocessing of S42 or S43 ends the command signal transmission processingand returns to S1 in FIG. 9.

FIG. 25 is an explanatory diagram of cancellation of registration of alocal ID by the sensor controller 31 and the stylus 2 a. In thisdiagram, an example of the case is depicted in which the stylus 2 a towhich the local ID #1 is allocated is in contact with the panel surfaceat first (L1) and moves therefrom to the outside of the sensing range SR(L2) and further moves to a height surpassing the uplink detectionheight AH (L3, L4). By the processing of the above-described S40 to S43,the sensor controller 31 cancels the registration of the local ID #1allocated to the stylus 2 a when a predetermined time (timecorresponding to the above-described threshold D) elapses after thestylus 2 a moves to the outside of the sensing range SR. In contrast,the stylus 2 can receive the uplink signal US if the stylus 2 does notexceed the uplink detection height AH even when being outside thesensing range SR. Thus, the stylus 2 does not cancel the registration ofthe local ID #k if its own height does not surpass the uplink detectionheight AH. The cancellation of the registration of the local ID #1 bythe stylus 2 a is carried out after a predetermined time elapses afterreception of the uplink signal US becomes impossible as explained inFIG. 17 to be described later.

Next, in FIG. 13 and FIG. 14, processing in the case in which the valueof the operation state of the local ID #k has been determined as the“first reset mode” at S21 in FIG. 11 is depicted. As depicted in FIG.13, at first, the sensor controller 31 in this case determines the valueof reset command non-issuance flag 1 of the local ID #k by referring tothe ID management table 70 (S50). If reset command non-issuance flag 1of the local ID #k is “TRUE” as the result, the sensor controller 31transmits a command signal (reset signal) that represents a reset orderof the local ID #k (S51). The stylus 2 that has received this commandsignal deletes the local ID #k stored in its memory 45 (see FIG. 2).Thereafter, the sensor controller 31 sets “FALSE” in reset commandnon-issuance flag 1 of the local ID #k (S52) and subsequently carriesout reception operation of the downlink signal DS (S53). At S53, even ifthe downlink signal DS including the local ID #k is received, the sensorcontroller 31 does not carry out operation based on the signal. However,the sensor controller 31 may carry out operation of determining thelocal ID in the downlink signal DS. If the local ID is a local ID otherthan the local ID #k, the sensor controller 31 may further carry outoperation based on the downlink signal DS (operation depicted in S34 toS36 in FIG. 12).

After S53, the sensor controller 31 may readjust the transmissionschedule (S54). This readjustment may be processing of returning, todefault values, the scan rate and the transmission continuation time ofthe downlink signal DS allocated to the local ID #k regarding which thereset order has been issued.

If determining at S50 that reset command non-issuance flag 1 of thelocal ID #k is “FALSE,” as depicted in FIG. 14, first the sensorcontroller 31 transmits a command signal that represents a settinginstruction of the local ID #k (S55). This is, in short, processing inthe next opportunity for transmission of the command signal relating tothe local ID #k after the transmission of the command signal thatrepresents the reset order of the local ID #k at S51. After transmittingthe command signal, the sensor controller 31 carries out receptionoperation of the downlink signal DS (S56) and determines whether or notthe downlink signal DS including the local ID #k has been received(S57).

If determining at S57 that the downlink signal DS including the local ID#k has been received only at one place in the panel surface, first thesensor controller 31 sets 0 in the deletion counter of the local ID #kin the ID management table 70 (S58). Next, the sensor controller 31performs processing of temporarily cancelling the registration of thelocal ID #k in the ID management table 70 and reregistering the local ID#k in the ID management table 70 (S59). Because the registration istemporarily cancelled, the value of the operation state of the local ID#k (see FIG. 8) returns to the “normal mode” here. Then, the sensorcontroller 31 derives the position of the stylus 2 based on a burstsignal in the received downlink signal DS (S60). In addition, if a datasignal in the downlink signal DS includes data other than the local ID#k, the sensor controller 31 extracts the data (S61). Thereafter, thesensor controller 31 readjusts the transmission schedule similarly toS17 (S62). After the end of S62, the sensor controller 31 ends thecommand signal transmission processing and returns to S1 in FIG. 9.

In FIG. 26, one example of operation of the sensor controller 31 and thestylus 2 relating to the first reset mode is depicted. In this example,both the styluses 2 a and 2 b simultaneously respond to a settinginstruction of the local ID #1 transmitted by the sensor controller 31.Such a situation possibly occurs when both the styluses 2 a and 2 bbecome the pen-down state during the transmission interval of the stylussearch signal also as depicted in FIG. 26. When detecting reception ofthe downlink signal DS including the local ID #1 at plural places(“overlapping is detected” in FIG. 26. In the flowchart, S13 in FIG.10), the sensor controller 31 transmits a command signal that representsa reset order of the local ID #1 (in the flowchart, S51 in FIG. 13).Thereafter, the sensor controller 31 transmits a command signal thatrepresents a setting instruction of the local ID #1 plural times (in theflowchart, S55 in FIG. 14).

Although details of operation of the stylus 2 will be described later,after receiving this command signal that represents the reset order ofthe local ID #1, the styluses 2 a and 2 b each cancel the registrationof the local ID #1 and generate the value of an ID setting wait counterto ignore subsequently-received setting instructions for a timeaccording to the value. After this ignorance period ends, the stylus 2that has received a command signal that represents a setting instructionof the local ID #1 transmitted by the sensor controller 31 (stylus 2 ain FIG. 26) transmits the downlink signal DS including the local ID #1and thereby the local ID #1 is anew registered in the ID managementtable 70 (“#1 is registered” in FIG. 26. In the flowchart, S59 in FIG.14). As above, according to the processing of the sensor controller 31and the stylus 2 in accordance with the present embodiment, even if aresponse is made from plural styluses 2 to a setting instructiontransmitted immediately after transmission of the stylus search signal,a local ID can be reallocated to only one of them rapidly. The stylus 2b, to which the local ID #1 is not allocated, starts communication withthe sensor controller 31 as the local ID #2 by receiving a commandsignal that represents a setting instruction of the local ID #2transmitted immediately after the next stylus search signal also asdepicted in FIG. 26.

Here, the example of FIG. 26 is based on the premise that a commandsignal that represents a reset order is received by both the styluses 2a and 2 b. However, the sensor controller 31 may transmit the commandsignal that represents a reset order in such a manner that the commandsignal is received by only one of the styluses 2 a and 2 b (if three ormore styluses 2 are simultaneously detected, only part of them).Specifically, the sensor controller 31 may acquire the position of eachof the styluses 2 a and 2 b on the panel surface based on the downlinksignal DS transmitted by each of the styluses 2 a and 2 b, and transmitthe command signal that represents a reset order locally (that is, onlyfrom a partial region of the sensor electrode 30) based on the acquiredposition in such a manner that the command signal is received by onlyeither one. Furthermore, if the styluses 2 a and 2 b can receive theuplink signal US by a proximity wireless communication measure(communication measure different from communication through capacitivecoupling using the sensor electrode 30) as described above, the commandsignal that represents a reset order may be transmitted to only eitherone of the styluses 2 a and 2 b by using the proximity wirelesscommunication measure. This makes it possible to reallocate a local IDto only the other of the styluses 2 a and 2 b without using the IDsetting wait counter. This point is the same also regarding the secondreset mode explained with FIG. 27 to be described later.

Referring back to FIG. 14, if determining at S57 that the downlinksignal DS including the local ID #k has been received at plural placesin the panel surface, the sensor controller 31 sets 0 in the deletioncounter of the local ID #k in the ID management table 70 (S63) and sets“TRUE” in reset command non-issuance flag 1 of the local ID #k again(S64). Thereafter, the sensor controller 31 ends the command signaltransmission processing and returns to S1 in FIG. 9. This is processingin the case in which the values of the above-described ID setting waitcounters accidentally correspond with each other. Due to setting “TRUE”in reset command non-issuance flag 1 of the local ID #k again at S64,the processing is performed again from the transmission of a commandsignal that represent a reset order (S51 in FIG. 13).

The sensor controller 31 in the case of determining at S57 that thedownlink signal DS including the local ID #k has not been receiveddetermines whether or not the deletion counter (see FIG. 8) of the localID #k is larger than the predetermined threshold D (S65). If determiningthat the deletion counter is not larger, the sensor controller 31increments the deletion counter of the local ID #k by 1(S68). On theother hand, if determining that the deletion counter is larger, thesensor controller 31 cancels the registration of the local ID #k bydeleting the row of the local ID #k from the ID management table 70(S66). Then, in order to allocate opportunities for transmission of thedownlink signal DS given to the stylus 2 corresponding to the local ID#k thus far to other styluses 2, the sensor controller 31 readjusts thetransmission schedule of the downlink signal DS and updates the IDmanagement table 70 based on the result thereof (S67). For example, inthe example of FIG. 26, the processing of S65 to S68 is performed ifboth the styluses 2 a and 2 b get out of the sensing range SR while thesensor controller 31 is transmitting the command signals that representthe setting instruction of the local ID #1.

Next, in FIG. 15, processing in the case in which the value of theoperation state of the local ID #k has been determined as the “secondreset mode” at S21 in FIG. 11 is depicted.

Here, processing of the sensor controller 31 and the stylus 2 in thesecond reset mode will be described in detail with reference to FIG. 27in advance.

As described with reference to FIG. 12, it is when two or more styluses2 simultaneously transmit the downlink signal DS including the local ID#k in response to not a command signal that represents a settinginstruction about the local ID #k but a command signal that represents adata transmission instruction of the local ID #k that the value of theoperation state of the certain local ID #k is set to the second resetmode. In FIG. 27, one example of the case in which such a state occursis depicted. In the example of this diagram, as the initial state, thelocal ID #1 is allocated to only the stylus 2 a and a local ID is notallocated to the stylus 2 b. When the stylus 2 a gets out of the sensingrange SR (clock time t1) in this situation, the downlink signal DS fromthe stylus 2 a becomes unreachable and thus the sensor controller 31cancels the registration of the local ID #1 after a predetermined time.However, as described with reference to FIG. 25, cancellation of theregistration of the local ID in the stylus 2 is carried out latercompared with the sensor controller 31. Therefore, in the example ofFIG. 27, cancellation of the registration of the local ID in the stylus2 has not been carried out even after the sensor controller 31 hascancelled the registration of the local ID #1.

Even in the state in which the stylus 2 a remains holding the local ID#1, when the stylus 2 b newly enters the sensing range SR (clock timet2), the stylus 2 b receives a command signal that is transmitted by thesensor controller 31 and represents a setting instruction of the localID #1 and, as a result, the sensor controller 31 allocates the local ID#1 to the stylus 2 b. Thereafter, when the stylus 2 a that remainsholding the local ID #1 enters the sensing range SR again (clock timet3), both the styluses 2 a and 2 b respond to a command signal that isaddressed to the local ID #1 and represents a data transmissioninstruction. This is the case in which the determination of “received atplural places” is made at S32 depicted in FIG. 12. In FIG. 15,processing for eliminating such overlapping of the local ID #1 (state inwhich plural styluses 2 hold the same local ID #k) is described.

Referring back to FIG. 15, the sensor controller 31 in this casedetermines the value of reset command non-issuance flag 2 of the localID #k at first (S70). If reset command non-issuance flag 2 of the localID #k is “TRUE” as the result, the sensor controller 31 transmits acommand signal (reset signal) that represents a reset order of the localID #k (S71) and sets “FALSE” in reset command non-issuance flag 2 of thelocal ID #k in the ID management table 70 (S72). This processing isperformed immediately after the sensor controller 31 detects overlappingof the local ID #k. In FIG. 27, the reset order immediately after“overlapping is detected” is equivalent to the reset order transmittedat S71. On the other hand, if determining at S70 that reset commandnon-issuance flag 2 of the local ID #k is “FALSE,” the sensor controller31 transmits a command signal that represents a data transmissioninstruction of the local ID #k (S73).

After the end of S72 or S73, the sensor controller 31 carries outreception operation of the downlink signal DS (S74). Then, the sensorcontroller 31 determines whether or not the downlink signal DS includingthe local ID #k has been received (S75).

If determining at S75 that the downlink signal DS including the local ID#k has been received, the sensor controller 31 derives the position ofthe stylus 2 based on a burst signal in the received downlink signal DS(S76). Here, as described in detail later, the stylus 2 is so configuredthat, if the present timing is not immediately after registration of anew local ID, even when receiving a command signal that represents areset order, the stylus 2 postpones the reset (cancellation ofregistration of the local ID) for a while and continues to carry outtransmission of the downlink signal DS as a response to a command signalthat represents a data transmission instruction. The length of thispostponement period is decided based on the value of an ID cancellationwait counter to be described later. Therefore, at S76, one or morepositions continue to be derived for a while.

The sensor controller 31 selects the position continuous with thepreviously-derived position from the one or more positions derived atS76 (S77). In the example of FIG. 27, the stylus 2 that communicateswith the sensor controller 31 until immediately before the sensorcontroller 31 detects overlapping is the stylus 2 b. Thus, at S77, theposition derived based on the downlink signal DS of the stylus 2 b isselected.

Subsequently, the sensor controller 31 determines whether or not theselection of the position at S77 is possible (S78). As described above,after receiving a command signal that represents a reset order, thestylus 2 continues the response to the command signal that represents adata transmission instruction for the period decided based on the valueof the ID cancellation wait counter. Therefore, possibly there is thecase in which the stylus 2 existing at the position continuous with thepreviously-derived position stops the response earlier than the otherstyluses 2. In this case, it is determined that the selection is notpossible at S78.

If determining that the selection is possible at S78, the sensorcontroller 31 sets 0 in the deletion counter of the local ID #k in theID management table 70 (S79) and extracts data included in a data signalin the downlink signal DS corresponding to the selected position (S80).Due to this, only the coordinates x and y that represent the position ofthe stylus 2 existing at the position continuous with thepreviously-derived position, the local ID, and the data are reported tothe electronic equipment controller 33. Furthermore, the sensorcontroller 31 readjusts the transmission schedule depending on thecontents of the data (for example, the case in which the extracted datais a global ID, or the like) (S81) and thereafter ends the commandsignal transmission processing and returns to S1 in FIG. 9.

If determining at S75 that the downlink signal DS including the local ID#k has not been received or if determining at S78 that the selection isnot possible, the sensor controller 31 determines whether or not thedeletion counter (see FIG. 8) of the local ID #k is larger than thepredetermined threshold D (S82). If determining that the deletioncounter is not larger, the sensor controller 31 increments the deletioncounter of the local ID #k by 1 (S85). On the other hand, if determiningthat the deletion counter is larger, the sensor controller 31 cancelsthe registration of the local ID #k by deleting the row of the local ID#k from the ID management table 70 (S83). This eliminates the case inwhich the local ID #k is decided as the transmission target at S20 inFIG. 11. Therefore, the transmission of the command signal thatrepresents a data transmission instruction of the local ID #k at S73 isalso stopped. Then, in order to allocate opportunities for transmissionof the downlink signal DS given to the stylus 2 corresponding to thelocal ID #k thus far to other styluses 2, the sensor controller 31readjusts the transmission schedule of the downlink signal DS andupdates the ID management table 70 based on the result thereof (S84).The sensor controller 31 that has ended the processing of S84 ends thecommand signal transmission processing and returns to S1 in FIG. 9.

The operation of the sensor controller 31 relating to the presentdisclosure is described in detail above. Next, the operation of thestylus 2 relating to the present disclosure will be described in detail.

As depicted in FIG. 16, first the stylus 2 determines the detectionstate of the sensor controller 31 (S100). If determining that thedetection state is the undetected state in which the sensor controller31 has not yet been detected as the result, the stylus 2 tries detectionof the above-described detection pattern c1 (S101). This processing isprocessing for detecting the stylus search signal intermittentlytransmitted by the sensor controller 31.

Next, the stylus 2 determines whether or not the detection pattern c1has been detected as the result of the trial at S101 (S102). Ifdetermining that the detection pattern c1 has not been detected as theresult, the stylus 2 makes a pause in the operation for a predeterminedtime (S103) and then returns to S100 to repeat the trial of detection ofthe detection pattern c1. The pause in the operation at S103 is forsuppressing the power consumption of the stylus 2 by intermittentlycarrying out the reception operation. On the other hand, if determiningat S102 that the detection pattern c1 has been detected, the stylus 2waits for the end of the stylus search signal (S104). As describedabove, the stylus search signal is a signal composed of repetition ofthe known detection pattern c1 and the delimiter pattern STP added tothe tail end. Therefore, the stylus 2 detects the end of the detectionpattern by detecting the delimiter pattern STP. Thereafter, the stylus 2sets the detection state of the sensor controller 31 to thealready-detected state (S105) and returns to S100.

If determining at S100 that the detection state is the already-detectedstate, the stylus 2 performs command signal reception processing (S106).

In FIG. 17, details of the command signal reception processing aredepicted. As depicted in this diagram, the stylus 2 that has started thecommand signal reception processing starts measurement of thenon-detection time of the uplink signal US (S110). Then, the stylus 2carries out reception operation of the command signal (S111) anddetermines whether or not a command signal has been received (S112).

If determining at S112 that a command signal has not been received, thestylus 2 determines whether or not a predetermined time has elapsed fromthe measurement of the non-detection time is started at S110 (S113).This predetermined time is a time shorter than one second, such asseveral hundreds of milliseconds for example. If determining that thepredetermined time has not elapsed here, the stylus 2 returns to S111and carries out the reception operation of the command signal again. Onthe other hand, if determining that the predetermined time has elapsed(that is, if the uplink signal US is not detected for the predeterminedperiod), the stylus 2 sets the detection state of the sensor controller31 to the undetected state (S114). In addition, if a local ID isregistered in the memory 45 (see FIG. 2), the stylus 2 cancels theregistration of the local ID by deleting it (S115). Thereafter, thestylus 2 ends the command signal reception processing and returns toS100 in FIG. 16. The processing of S114 and S115 is processing performedwhen the stylus 2 moves to a height that surpasses the uplink detectionheight AH depicted in FIG. 1 and becomes incapable of receiving theuplink signal US.

Here, if a local ID has been already registered in the memory 45, thestylus 2 may cancel the registration of the local ID not only when theuplink signal US is not detected for the predetermined period asdescribed above but also when the uplink signal US including the localID registered in the memory 45 is not detected for the predeterminedperiod. Due to this, for example when the state occurs in which, fromthe viewpoint of the stylus 2, the uplink signal US can be detected butthe uplink signal US including its own local ID is not detected nomatter how long the stylus 2 waits, such as when the stylus 2 stores alocal ID in the memory 45 and remains at a position lower than theuplink detection height AH but the local ID is not registered (has beenalready cancelled) in the sensor controller 31, a new local ID can beallocated from the sensor controller 31 to the stylus 2 without movementof the stylus 2 to a position higher than the uplink detection heightAH.

On the other hand, if determining at S112 that a command signal has beenreceived, the stylus 2 resets the value of the non-detection time anddetermines which of “setting instruction,” “reset order,” and “datatransmission instruction” the contents of a command represented by thereceived command signal are (S117).

<D. Operation in Response to ID Setting Instruction>

In FIG. 18, processing in the case in which the command is determined asthe “setting instruction” at S117 in FIG. 17 is depicted. In this case,first the stylus 2 determines whether or not the ID setting wait counteris 0 (S120). The ID setting wait counter represents the period duringwhich the stylus 2 that has received an ID setting instruction does notimmediately reflect (ignores) the setting instruction although thesetting instruction is present. The ID setting wait counter is set inS135 to be described later and is 0in the initial state. If the IDsetting wait counter is not 0, the stylus 2 performs processing ofdecrementing the ID setting wait counter by 1 (S125). Thereafter, thestylus 2 ends the command signal reception processing and returns toS100 in FIG. 16. In this case, the setting instruction of a local ID bythe sensor controller 31 is ignored by the stylus 2.

On the other hand, if the ID setting wait counter is 0, the stylus 2determines whether or not a local ID has been already registered in itsown memory 45 (see FIG. 2) (S121). If determining that a local ID hasbeen already registered here, the stylus 2 ends the command signalreception processing without executing particular processing and returnsto S100 in FIG. 16. On the other hand, the stylus 2 in the case ofdetermining that a local ID has not been already registered extracts thelocal ID from the command signal and registers the local ID in its ownmemory 45 (S122). Then, the stylus 2 transmits the downlink signal DSincluding the registered local ID (S123) and sets “TRUE” in aprovisional setting flag (S124). Thereafter, the stylus 2 ends thecommand signal reception processing and returns to S100 in FIG. 16. Thatthe provisional setting flag is “TRUE” means that the setting of thelocal ID is provisional. That the provisional setting flag is “FALSE”means that the local ID held in the memory is settled.

<E. Operation in Response to Reset Order>

In FIG. 19, processing in the case in which the command is determined asthe “reset order” at S117 in FIG. 17 is depicted. The stylus 2 in thiscase first determines whether or not the received command signalincludes the already-registered local ID (S130). If determining that thecommand signal does not include the already-registered local ID, thestylus 2 ends the command signal reception processing without executingparticular processing and returns to S100 in FIG. 16. This is processingfor ignoring the command signal that is not addressed to its own self.On the other hand, if determining that the command signal includes thealready-registered local ID, subsequently the stylus 2 determineswhether or not the writing pressure detected by the writing pressuredetecting sensor 23 (FIG. 24) surpasses 0 (S131). If the writingpressure surpasses 0 as the result, the stylus 2 ends the command signalreception processing without executing particular processing and returnsto S100 in FIG. 16. This means that the processing is continued withoutobeying the reset order in the case in which the stylus 2 has beenalready used on the panel operation surface and pen touch operation isbeing carried out or the like (typically the case in which renderingprocessing or the like with use of the stylus 2 has been started). Onthe other hand, if the writing pressure is 0, subsequently the stylus 2determines the value of the provisional setting flag (S132).

If the provisional setting flag is “TRUE,” the stylus 2 cancels theregistration of the local ID by deleting the local ID from the memory 45(S133). Thereby, the stylus 2 becomes the state in which a local ID isunregistered. Subsequently, the stylus 2 sets “FALSE” in the provisionalsetting flag (S134) and generates the ID setting wait counter (S135).Thereafter, the stylus 2 ends the command signal reception processingand returns to S100 in FIG. 16.

That it is determined at S132 that the provisional setting flag is“TRUE” means that the command signal that represents the reset order istransmitted immediately after the stylus 2 has registered the local ID.This is the case in which, as exemplified in FIG. 26, plural styluses 2respond to a setting instruction of the local ID transmitted by thesensor controller 31. The ID setting wait counter generated at S135represents the period during which the stylus 2 that has received areset order in such a case ignores the setting instruction. It sufficesthat the values of the ID setting wait counter and the ID cancellationwait counter generated in S136 to be described later are valuesdifferent for each of the chassis of the styluses 2. The values may begenerated from a serial number of a global ID or the like or valuesprioritized according to the device type may be predetermined.Alternatively, the values may be generated by a random number generator.Due to the ignorance of the setting instruction by the respectivestyluses 2 for the period according to the ID setting wait counter inthis manner, it becomes possible to reallocate the same local ID to onlyone stylus 2 of them as described above with reference to FIG. 26.

Referring back to FIG. 19, if determining at S132 that the provisionalsetting flag is “FALSE,” the stylus 2 generates the ID cancellation waitcounter (S136) and sets “TRUE” in a reset-in-execution flag (S137).Then, the stylus 2 ends the command signal reception processing andreturns to S100 in FIG. 16.

The case in which it is determined at S132 that the provisional settingflag is “FALSE” means that the command signal that represents the resetorder is transmitted not when the local ID is provisionally set, such asimmediately after the stylus 2 has registered the local ID, but afterthe local ID has been already settled. This is the case in which, asdescribed with reference to FIG. 27, two or more styluses 2simultaneously transmit the downlink signal DS including the same localID in response to a command signal that represents a data transmissioninstruction. The ID cancellation wait counter generated at S136represents the time by which the stylus 2 that has received a resetorder in such a case delays execution of registration cancellation ofthe local ID. Due to the delaying of execution of registrationcancellation of the local ID by the respective styluses 2 for the periodaccording to the ID cancellation wait counter in this manner, it becomespossible for the sensor controller 31 to continuously carry out positiondetection of the stylus 2 and data acquisition from the stylus 2 asexemplified in FIG. 27. As described with reference to FIG. 15, in sucha case, the sensor controller 31 deems only the downlink signal DScorresponding to the position continuous with the previous derivedposition as the target of processing (S76 to S81). Thus, positiondetection and data acquisition are carried out regarding not the stylus2 that has newly entered the sensing range SR (in FIG. 27, stylus 2 a)but only the stylus 2 that continuously remains in the sensing range SR(in FIG. 27, stylus 2 b). Therefore, with respect to a local IDgenerated when another stylus 2 kept lower than the uplink detectionheight AH (second stylus 2) enters the sensing range SR with theintermediary of a time lag after a user has caused a certain stylus 2(first stylus 2) to make pen touch and begun to use the certain stylus 2on the panel surface, the sensor controller 31 can implement operationof detecting coordinates by continuously using the coordinate values ofthe stylus 2 having higher probability of being the first stylus 2 andreporting the coordinates to the electronic equipment controller 33.

<F. Operation in Response to Data Transmission Instruction>

In FIG. 20, processing in the case in which the command is determined asthe “data transmission instruction” at S117 in FIG. 17 is depicted. Thestylus 2 in this case first determines whether or not the receivedcommand signal includes the already-registered local ID (S140). Ifdetermining that the command signal does not include thealready-registered local ID, the stylus 2 ends the command signalreception processing about the command signal that is presently receivedwithout executing particular processing and returns to S100 in FIG. 16to start the next command signal reception processing. This isprocessing for ignoring the command signal that is not addressed to itsown self and starting preparation for a response to the next command. Onthe other hand, if determining that the command signal includes thealready-registered local ID, the stylus 2 sets “FALSE” in theprovisional setting flag (S141) and subsequently determines the value ofthe reset-in-execution flag (S142).

If the reset-in-execution flag is “FALSE,” the stylus 2 transmits thedownlink signal DS including the already-registered local ID and datainstructed to be transmitted by the command signal (S147). Then, thestylus 2 ends the command signal reception processing and returns toS100 in FIG. 16. This processing is the normal response to the commandsignal that represents the data transmission instruction.

On the other hand, if determining at S142 that the reset-in-executionflag is “TRUE,” first the stylus 2 determines whether or not the IDcancellation wait counter is 0 (S143). The initial state of the IDcancellation wait counter is 0 as with the ID setting wait counter.However, immediately after the stylus 2 receives a reset order at atiming that is not immediately after registration of a local ID, a valuethat is not 0 is set in the ID cancellation wait counter at S136. Ifdetermining that the ID cancellation wait counter is not 0, the stylus 2performs processing of decrementing the ID cancellation wait counter by1 (S146) and thereafter transmits the downlink signal DS including thealready-registered local ID and data instructed to be transmitted by thecommand signal (S147). Then, the stylus 2 ends the command signalreception processing and returns to S100 in FIG. 16. This processing ofS146 and S147 is processing in the case in which the stylus 2 delaysexecution of registration cancellation of the local ID as described withreference to FIG. 27.

On the other hand, if determining at S143 that the ID cancellation waitcounter is 0, the stylus 2 cancels the registration of the local ID bydeleting the local ID from the memory 45 (S144) and sets “FALSE” in thereset-in-execution flag (S145). Then, the stylus 2 ends the commandsignal reception processing and returns to S100 in FIG. 16. Thereby, thedelayed registration cancellation of the local ID is performed.

As described above, according to the sensor controller 31 and the stylus2 in accordance with the present embodiment, the sensor controller 31allocates a local ID to the stylus 2 by a command signal that representsa setting instruction and makes the local ID be included in anothercommand signal. Thereby, the sensor controller 31 can specify the stylus2 that should respond to the command signal. Therefore, it becomespossible to flexibly change the timings when the respective stylusestransmit the downlink signal DS.

Furthermore, the sensor controller 31 can specify the stylus 2 thatshould respond to the command signal by only making one value of a localID be included in the command signal. Thus, it becomes possible todecrease the size of the command signal compared with the case in whichthe timings when the respective styluses 2 transmit the downlink signalDS are decided by a negotiation carried out in advance.

Moreover, if determining that a received command signal does not includethe already-registered local ID at S130 or S140, the stylus 2 canimmediately move to reception operation of the next command signal(S111). Therefore, it becomes possible to favorably receive the nextcommand signal irrespective of the length of the downlink signal DStransmitted by the other styluses 2.

Although the preferred embodiment of the present disclosure is describedabove, it is obvious that the present disclosure is not limited to suchan embodiment at all and the present disclosure can be carried out invarious modes in such a range as not to depart from the gist thereof.

For example, in the above-described embodiment, description is madebased on the assumption that the position detecting system 1 includesthe two pen-type styluses 2 a and 2 b and the one ruler-type stylus 2 c.However, the number of styluses 2 included in the position detectingsystem 1 is not limited thereto. The present disclosure can be appliedto the position detecting system 1 including plural styluses 2irrespective of the form.

FIG. 28 and FIG. 29 are each a time chart depicting signals transmittedand received between the styluses 2 a and 2 b and the sensor controller31 according to a first modification example of the embodiment of thepresent disclosure. In FIG. 28, a scene in which the sensor controller31 registers the stylus 2 a and thereafter further registers the stylus2 b is depicted similarly to FIG. 22. In FIG. 29, a scene in whichnormal writing by the styluses 2 a and 2 c is being carried out afterthe sensor controller 31 readjusts the transmission schedule based onthe device type of each of the styluses 2 a and 2 c is depictedsimilarly to FIG. 24.

In the present modification example, communication between the styluses2 a and 2 b and the sensor controller 31 is carried out by theabove-described frame communication. This frame communication is carriedout by using frames F1, F2, . . . each including four slots T1 to T4.The number of slots in one frame is not limited to four. As describedabove, each frame is the display operation period of the liquid crystalpanel 32 (see FIG. 1) and the timing of each slot is decided based onthe blank period of the liquid crystal panel 32. The sensor controller31 decides the timing and time length of each slot and the number ofslots included in each frame by observing noise generated from theliquid crystal panel 32 or acquiring information from the liquid crystalpanel 32. These pieces of decided information are notified from thesensor controller 31 to the stylus 2 by the uplink signal US.

The sensor controller 31 is configured to transmit the stylus searchsignal every predetermined number (in FIG. 28, three) frames by usingthe first slot T1 thereof. Furthermore, the sensor controller 31 isconfigured to transmit a command signal at the beginning of each of theother slots. Meanwhile, the stylus 2 is configured to, when receivingthe command signal, transmit the downlink signal DS in response to thecommand signal.

Also in the present modification example, the transmission continuationtime of the downlink signal DS possibly differs depending on thespecifications of the stylus 2. If acquiring the transmissioncontinuation time of the downlink signal DS of the stylus 2 due toreception of a global ID, the sensor controller 31 decides thetransmission schedule based on the acquired transmission continuationtime of the downlink signal DS and writes the transmission schedule tothe ID management table 70. Then, the sensor controller 31 controls thetransmission interval of the command signal in order to realize thewritten transmission continuation time of the downlink signal DS. If thetransmission continuation time of the downlink signal DS is too long tofall within one slot, the sensor controller 31 realizes the transmissioncontinuation time of the downlink signal DS by skipping transmission ofthe uplink signal US at the beginning of the slot.

The present modification example is the same as the above-describedembodiment in the other points. Therefore, also according to the presentmodification example, it is possible to register a new local ID in boththe stylus 2 and the sensor controller 31 by a command signal thatrepresents a setting instruction of the local ID as depicted in FIG. 28,and it is also possible to change the scan rate depending on the localID as exemplified in FIG. 29.

As described above, according to the present modification example, thesensor controller 31 transmits the command signal including the value ofthe local ID every transmission time. Thus, the sensor controller 31 canspecify the stylus 2 that should transmit the downlink signal DS in thetransmission time. Therefore, it becomes possible to flexibly changeallocation of the transmission time to each stylus 2 in units of theslot shorter than the frame. Furthermore, by only making one value ofthe local ID be included in the command signal, it becomes possible toorder allocation of the transmission time (in the present modificationexample, slot) from the sensor controller 31 to each stylus 2. Thus, itbecomes possible to decrease the size of the uplink signal for orderingthe allocation of the slot as the transmission time compared with thecase in which the uplink signal for ordering the allocation of the slotis broadcast to each stylus on each frame basis as described above.

FIG. 30 is a time chart depicting another example of signals transmittedand received between the stylus 2 and the sensor controller 31 accordingto the present modification example. With reference to this FIG. 30, thepresent modification example will be described below again in moredetail from another point of view.

As depicted in FIG. 30, plural horizontal blanking periods HB aredisposed in one operation cycle VT of the liquid crystal panel 32 (seeFIG. 1) corresponding to one frame. In the latter half of the horizontalblanking period HB, processing of returning the pixels of the drivingtarget from the right end of the screen (or predetermined regionobtained by dividing the screen into plural regions) to the left end andthe electronic equipment controller 33 suspends drive processing of thepixels during this processing. That is, the latter half of thehorizontal blanking period HB serves as the above-described blank periodBP. In FIG. 30, an example in which n (n is an integer equal to orlarger than 3) blank periods BP exist in one frame is depicted. In thiscase, slots that can be used for communication between the stylus 2 andthe sensor controller 31 are n slots of slots T1 to Tn.

The sensor controller 31 is configured to transmit the stylus searchsignal by using the first slot T1 of the frame in each frame for exampleand transmit a command signal that represents a setting instruction(hereinafter, referred to as “first signal”) in theimmediately-subsequent slot T2. Furthermore, the sensor controller 31 isconfigured to transmit a command signal including a local ID regardingwhich an instruction of setting has been made by the setting instruction(hereinafter, referred to as “second signal”) in the subsequent slots T3to Tn. The first signal is a signal that gives the stylus 2 a command ofa setting instruction or the like to set a local ID and therefore thissignal may be referred to as a command signal. In contrast, the secondsignal is a signal that gives each of the styluses 2 only thetransmission timing and therefore this signal may be referred to as atiming signal. Moreover, the first signal is a signal that gives acommand and supplies a reference timing of the frame to the whole systemand the second signal is a signal that gives the respective individualstyluses the transmission timing. Therefore, the former may be referredto as a first timing signal and the latter may be referred to as asecond timing signal.

Meanwhile, the stylus 2 is configured to detect the stylus search signaland the first signal supplied to the sensor electrode 30 (sensorelectrode group) of the electronic equipment 3 in each frame forexample, and determine whether or not the detected first signalrepresents a setting instruction of a local ID, and write (register) thevalue of the local ID specified by the setting instruction to the memory45 if determining that the first signal represents the settinginstruction. Furthermore, the stylus 2 is configured to transmit adownlink signal that is a response to the setting instruction(hereinafter, referred to as “second downlink signal”) to the sensorcontroller 31 in response to the detection of the first signal. Thesensor controller 31 that has received this second downlink signalperforms processing of registering the value of the corresponding localID in the ID management table 70 as described above. In FIG. 30, thestylus 2 transmits the second downlink signal in the slot in which thestylus 2 has detected the first signal (in the example of FIG. 30, slotT2). However, if it is impossible to ensure a sufficient transmissiontime in the slot, or the like, the second downlink signal may betransmitted in the immediately-subsequent slot (in the example of FIG.30 slot T3). Moreover, without fixing to the same slot as the firstsignal or the immediately-subsequent slot, the stylus 2 may use a slotin which the second signal including a predetermined local ID defined inadvance has been transmitted by the sensor controller 31 as the slot inwhich the second downlink signal is transmitted. This makes it possibleto flexibly specify the transmission timing of the second downlinksignal, which is a response signal, from the side of the sensorcontroller 31 according to the length and placement of one blank periodBP, the gap time taken for switching between transmission and receptionof the stylus 2, or the like for example.

The stylus 2 that has written the value of the local ID to the memory 45repeatedly detects the second signal supplied to the sensor electrode 30of the electronic equipment 3 in each of one or more slots included inthe frame, and compares the values of the local ID included in thedetected second signal and the local ID stored in the memory 45 everytime the stylus 2 detects the second signal. If the values correspondwith each other, the stylus 2 transmits, to the sensor controller 31, adownlink signal that is a response to the second signal (hereinafter,referred to as “first downlink signal”) by using the electrode 21(electrodes 21_1 to 21_n if the stylus 2 is the stylus 2 c, which is aruler-type device). Because that the values of the local ID correspondwith each other is employed as the transmission condition of the firstdownlink signal as above, the stylus 2 does not transmit the firstdownlink signal in one frame if none of the second signals transmittedplural times in the one frame includes the value of the local ID writtento the memory 45.

Here, the second signal may be a signal that merely notifies a local IDand the timing of the blank period corresponding to the slot. In thiscase, the second signal may be a signal with a shorter time length thanthe first signal. For example, if only two kinds of local ID exist (thatis, if the number of styluses 2 that can simultaneously communicate withthe sensor controller 31 is only two), the second signal may be a signalincluding only one above-described symbol. Specifically, the secondsignal may be a signal that represents either of two kinds of bitsequence non-corresponding values “P” and “M” or may be a signal thatrepresents either of a bit sequence corresponding value converted to “0”in the stylus 2 and a bit sequence corresponding value converted to “1”in the stylus 2 (that is, signal in which only a bit value thatrepresents a local ID is included). Employing a signal having a shorttime length as above as the second signal allows the stylus 2 totransmit the first downlink signal in the slot in which the stylus 2 hasdetected the second signal including the local ID stored in the memory45 as depicted in FIG. 30. This is suitable particularly for the case inwhich it is difficult to ensure a sufficient communication time becausethe sensor electrode 30 is used also for a use purpose other thanposition detection operation as in a position detecting system of thein-cell type.

The first signal may include a value of a symbol for discrimination fromthe second signal. In this case, this value of the symbol is a valuethat represents a setting instruction of a local ID. If the first signalincludes a value of a symbol for discrimination from the second signalas above, it is preferable to configure the stylus 2 in such a mannerthat the stylus 2 does not employ the first signal as a trigger oftransmission of the first downlink signal and is triggered to transmitthe first downlink signal by detection of the second signal.

The present modification example is described above again in more detailfrom another point of view.

FIG. 31 is a time chart depicting signals transmitted and receivedbetween the stylus 2 and the sensor controller 31 according to a secondmodification example of the embodiment of the present disclosure. Thepresent modification example is different from the first modificationexample in how to use each slot in the frame. A description will be madebelow with focus on the different point.

The sensor controller 31 according to the present modification examplecollectively transmits the stylus search signal and the first signal inthe slot T1 of each frame. In FIG. 31, the stylus search signal and thefirst signal are drawn in such a manner as to be divided in terms oftime for convenience. However, the actual transmission method is notlimited to such a method based on time sharing. It suffices for thesignal including the stylus search signal and the first signal to be asignal that is a signal transmitted in each frame and serves as thetiming basis of frame synchronization and has a function including acommand such as a command to make a setting instruction of a local ID.

In the present modification example, the slot T2 is used as a period ofa response by the stylus 2 to the first signal. The stylus 2 that hasreceived the first signal in the slot T1 transmits the second downlinksignal, which is a response to the setting instruction, by using theslot T2. The sensor controller 31 does not carry out particular signaltransmission in the slot T2. The slot T2 is not continuous with the slotT1 and is disposed to be separated by the driving time of pixels.Therefore, even when a delay is caused in checking the cyclic redundancycheck (CRC) and so forth included in the first signal by the stylus 2after receiving the first signal, it is possible to ensure the time(gap) necessary for switching from the reception to transmission. Theresponse period does not necessarily have to be disposed in the slot T2immediately subsequent to the slot T1, and the sensor controller 31 mayspecify this response period by transmitting the second signal includinga predetermined local ID similarly to the first modification example.

In the present modification example, the slots T3 to Tn are used as adata transmission period. In this period, similarly to the firstmodification example, the sensor controller 31 transmits the secondsignal and the stylus 2 transmits the first downlink signal as aresponse to this second signal. The contents of the second signal andthe first downlink signal may be the same as the first modificationexample.

Also according to the present modification example, the sensorcontroller 31 transmits the command signal including the value of thelocal ID every transmission time. Thus, the sensor controller 31 canspecify the stylus 2 that should transmit the downlink signal DS (firstdownlink signal) in the transmission time. Therefore, it becomespossible to flexibly change allocation of the transmission time to eachstylus 2 in units of the slot shorter than the frame. Furthermore, byonly making one value of the local ID be included in the command signal,it becomes possible to order allocation of the transmission time (in thepresent modification example, slot) from the sensor controller 31 toeach stylus 2. Thus, it becomes possible to decrease the size of theuplink signal for ordering the allocation of the slot as thetransmission time compared with the case in which the uplink signal forordering the allocation of the slot is broadcast to each stylus on eachframe basis as described above.

FIG. 32 is a flowchart depicting a processing flow of the stylus 2according to a third modification example of the embodiment of thepresent disclosure. The present modification example is different fromthe above-described embodiment in that the command signal thatrepresents the “data transmission instruction” doubles as the “settinginstruction,” in that the period during which the stylus 2 ignores thesetting instruction (FIG. 26) is not set, in that the stylus 2 that hasreceived a reset order postpones cancellation of registration of thelocal ID (FIG. 27) is not set, in that determination of the writingpressure is not carried out before registration of the local ID iscancelled (cancellation of registration of the local ID is carried outirrespective of the writing pressure), and so forth. Operation of thestylus 2 according to the present modification example will be describedbelow with reference to FIG. 32.

The stylus 2 according to the present modification example first triesdetection of the stylus search signal (S200) and determines whether ornot the stylus search signal has been detected as the result (S201).Concrete contents of the stylus search signal and the method of thedetection may be the same as the above-described embodiment. In thiscase, it is when the delimiter pattern STP is detected that the positivedetermination is made at S201.

If obtaining the negative determination at S201, the stylus 2 returns toS200 and repeats the trial of detection of the stylus search signal. Onthe other hand, the stylus 2 in the case of obtaining the positivedetermination S201 carries out reception operation of the command signal(S202) and determines whether or not a command signal has been received(S203). The processing of S202 and S203 is the same processing asperformed at S111 and S112 depicted in FIG. 17.

If obtaining the negative determination at S203, the stylus 2 determineswhether or not a predetermined time has elapsed from the last receptionof the command signal (S204). If determining that the predetermined timehas not elapsed as the result, the stylus 2 returns to S202 and repeatsthe reception operation of the command signal. In the case in which thestylus 2 determines that the predetermined time has elapsed, if a localID is registered in the memory 45 (see FIG. 2) at the timing, the stylus2 cancels the registration of the local ID by deleting the local ID fromthe memory 45 (S205) and returns to S200.

The stylus 2 in the case of obtaining the positive determination at S203determines which of “reset order” and “data transmission instruction”the contents of a command represented by the received command signalare. In the present modification example, the command signal thatrepresents the “data transmission instruction” doubles as the “settinginstruction” as described above. Thus, the contents of the commanddiscriminated at S203 are two kinds different from S117 in FIG. 17, inwhich three kinds of command contents are discriminated.

If determining at S206 that the command is the “reset order,” the stylus2 determines whether or not the received command signal includes thealready-registered local ID (S207). Then, if determining that thecommand signal does not include the already-registered local ID, thestylus 2 returns to S202 and repeats the reception operation of thecommand signal. If determining that the command signal includes thealready-registered local ID, the stylus 2 cancels the registration ofthe local ID by deleting the local ID from the memory 45 (S208) andreturns to S200.

If determining at S206 that the command is the “data transmissioninstruction,” subsequently the stylus 2 determines whether or not alocal ID has been already registered in its own memory 45 (S209). Then,if a local ID has not been registered, the stylus 2 extracts a local IDfrom the received command signal and registers the local ID in thememory 45 (S210). Then, the stylus 2 transmits the downlink signal DSincluding the registered local ID and data instructed to be transmittedby the command signal (S211). Thereafter, the stylus 2 returns to S202and repeats the reception operation of the command signal.

The stylus 2 in the case of determining at S209 that a local ID has beenalready registered subsequently determines whether or not the receivedcommand signal includes the already-registered local ID (S212). Then, ifdetermining that the command signal does not include thealready-registered local ID, the stylus 2 returns to S202 and repeatsthe reception operation of the command signal. On the other hand, ifdetermining that the command signal includes the already-registeredlocal ID, the stylus 2 transmits the downlink signal DS including thealready-registered local ID and data instructed to be transmitted by thecommand signal (S213). Thereafter, the stylus 2 returns to S202 andrepeats the reception operation of the command signal.

Also according to the present modification example, the sensorcontroller 31 allocates a local ID to the stylus 2 by a command signalthat represents a setting instruction and makes the local ID be includedin another command signal. Thereby, the sensor controller 31 can specifythe stylus 2 that should respond to the command signal. Therefore, itbecomes possible to flexibly change the timings when the respectivestyluses transmit the downlink signal DS.

Furthermore, the sensor controller 31 can specify the stylus 2 thatshould respond to the command signal by only making one value of a localID be included in the command signal. Thus, it becomes possible todecrease the size of the command signal compared with the case in whichthe timings when the respective styluses 2 transmit the downlink signalDS are decided by a negotiation carried out in advance.

Moreover, in the present modification example, the command signal thatrepresents the “data transmission instruction” doubles as the “settinginstruction.” Thus, the stylus 2 can transmit the normal downlink signalDS including data at S211 immediately after a local ID is registered.Therefore, the opportunity for transmission of the downlink signal DScan be increased by one time compared with the case in which the replyto the “setting instruction” is carried out by the downlink signal DSthat does not include data.

In the above-described embodiment, the downlink signal DS is configuredto include two signals, the burst signal and the data signal. However,the downlink signal DS may include only one of these two signals, suchas only the burst signal or only the data signal.

Furthermore, in the above-described embodiment, the example in whichtransmission of a global ID is carried out by using the downlink signalDS using capacitive coupling is described. However, because the globalID is static information differently from the handling state thatchanges depending on the timing of reception of the uplink signal US,the global ID may be notified from the stylus 2 to the sensor controller31 by another proximity wireless communication measure such as Bluetooth(registered trademark) for example. Due to this, in communication usingcapacitive coupling, the communication time for transmitting the globalID can be reduced. This can increase the opportunity for transmission ofthe data signal including handling states such as a writing pressurevalue and the pressing-down state of a switch.

Moreover, in the above-described embodiment, it is explained that thereare two kinds of signals, the stylus search signal and the commandsignal, in the uplink signal US. However, the stylus search signal mayinclude a local ID setting instruction command to the new undetectedstylus 2. This allows the stylus 2 to immediately set a local ID at thetiming of reception of the stylus search signal.

Furthermore, in the above-described embodiment, the example is describedin which the values of symbols that take multiple values such as “P,”“M,” and “0 to 15” are used as the transmission method of the controlinformation c2, the detection pattern c1, the delimiter pattern STP, andso forth. However, these pieces of information or patterns may betransmitted by another transmission method, e.g. a transmission methodusing a modulation system such as OOK or PSK.

Moreover, in the above-described embodiment, the value of the local IDis cited as an example of information stored in the memory 45 of thestylus 2. However, other various kinds of information may be stored inthe memory 45. For example, the memory 45 may store, besides the localID, a state to identify whether pairing of the relevant stylus 2 withthe sensor controller 31 has been carried out or not been carried out(hereinafter, referred to as “pairing state”). Here, the state in whichthe pairing has been carried out corresponds to the state in which alocal ID is stored in the memory 45, and the state in which the pairinghas not been carried out corresponds to the state in which a local ID isnot stored in the memory 45. In this case, the controller 44 of thestylus 2 may set the pairing state stored in the memory 45 to the stateindicating that the pairing has been carried out after writing a localID represented by a setting instruction to the memory 45. Furthermore,the controller 44 may set the pairing state to the state indicating thatthe pairing has not been carried out if deleting the local ID stored inthe memory 45 and if determining that a command signal (second commandsignal described in the third modification example) includes a resetorder.

Furthermore, the electronic equipment 3 may be an apparatus other thanthe tablet computer like that depicted in FIG. 1. For example, theelectronic equipment 3 may be a large-size apparatus like a board onwhich plural persons simultaneously carry out drawing while usingstyluses, such as an electronic blackboard installed on a wall of aclassroom of a school. Moreover, as one kind of stylus 2, the auxiliarydevice is explained by taking an electronic ruler with a straight lineshape as an example. However, the auxiliary device may include variouskinds of tools such as an electronic blackboard eraser with a circularshape or polygonal shape. A pen move by the stylus 2 that is anelectronic blackboard eraser plays a role in erasing or cutting a locuswritten by another stylus 2 (for example, loci st1 to st3 depicted inFIG. 1). In addition, if the auxiliary device has a shape such as acircular shape or polygonal shape, electrodes may be disposed atarbitrary positions adaptively to the shape.

It is to be noted that the embodiment of the present disclosure is notlimited to the foregoing embodiment, and that various changes can bemade without departing from the spirit of the present disclosure.

What is claimed is:
 1. A stylus that operates in synchronization with asensor controller connected to a sensor electrode group, the styluscomprising: an electrode; a memory; and a processor, wherein theprocessor, in operation: detects a first signal supplied to the sensorelectrode group in each frame of a plurality of frames, wherein eachframe corresponds to a display operation period of a display panel,determines whether the first signal represents a setting instruction ofa local identifier, in response to determining that the first signalrepresents the setting instruction of the local identifier, determineswhether a counter value is equal to a first value, in response todetermining that the counter value is not equal to the first value,ignores the setting instruction and changes the counter value, inresponse to determining that the counter value is equal to the firstvalue, stores a value of the local identifier specified by the settinginstruction to the memory, repeatedly detects a second signal suppliedto the sensor electrode group in each of one or more slots included inthe frame, wherein the second signal that notifies one or more timing ofone or more blank periods corresponding to the one or more slots in theframe, and compares a value of a local identifier included in the secondsignal detected and the value of the local identifier specified by thesetting instruction and stored in the memory every time the processordetects the second signal, and transmits a first downlink signal to thesensor controller using the electrode in response to determining thatthe value of the local identifier included in the second signal and thevalue of the local identifier specified by the setting instruction andstored in the memory correspond with each other.
 2. The stylus accordingto claim 1, wherein the second signal has a shorter time length than thefirst signal.
 3. The stylus according to claim 2, wherein only a valuethat represent the local identifier is included in the second signal. 4.The stylus according to claim 1, wherein the processor does not employthe first signal as a trigger of transmission of the first downlinksignal, and the processor is triggered to transmit the first downlinksignal by detection of the second signal.
 5. The stylus according toclaim 1, wherein the processor transmits a second downlink signal as aresponse to the setting instruction in response to detection of thefirst signal.
 6. The stylus according to claim 5, wherein the processortransmits the second downlink signal in a same slot as the first signalthat represents the setting instruction or in an immediately-subsequentslot.
 7. The stylus according to claim 5, wherein the processortransmits the second downlink signal in a slot in which the processorhas detected the second signal including a predetermined localidentifier.
 8. The stylus according to claim 1, wherein the processordetermines whether the second signal includes a reset order, and deletesthe value of the local identifier stored in the memory if the secondsignal is determined to include the reset order.
 9. The stylus accordingto claim 8, wherein the processor holds, in the memory, a state thatidentifies whether pairing of the stylus with the sensor controller hasbeen carried out, and the processor sets the state to a state indicatingthat the pairing has been carried out after writing the local identifierto the memory, and the processor sets the state to a state indicatingthat the pairing has not been carried out if the second signal isdetermined to include the reset order.
 10. The stylus according to claim1, wherein the processor does not transmit the first downlink signal inone frame if none of the second signals transmitted a plurality of timesin the one frame includes the value of the local identifier written tothe memory.